SEQUENCING INSTRUCTION IN CHEMISTRY: SIMULATION OR TRADITIONAL FIRST?
by
Sharmila Pillay B.Sc., The University of South Pacific, 1994 B.Ed., The University of British Columbia, 1999
A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF ARTS
in
THE FACULTY OF GRADUATE STUDIES (Science Education)
THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)
October 2010
©Sharmila Pillay, 2010 ABSTRACT
The purpose of this study is to investigate how a technology-enhanced lesson based on the principles of model-based teaching and learning can contribute to student understanding of two challenging topics in chemistry: Le Chatelier’s Principle and Chemical Equilibrium. A computer simulation program was utilized that contained multiple digital representations, such as: a chemical formula view, a slider view, a graph view, a description view, a prediction view, a molecular view and a dynamic analogy view. The study also addressed the sequencing of instruction, changing when computer simulation was introduced in two chemistry 12 classes (n=46). One class of 22 students received instruction in a traditional form (lecture, labs) and then interacted with the simulation and the other class of 24 students interacted with simulations first and then received a traditional form of instruction. Both the classes participated in a pre-test, mid-test, post-test, surveys and interviews designed to assess students’ conceptual understanding of chemical equilibrium. Statistical analysis of the tests revealed that a computer simulation such as Technology-Enhanced Model-Based
Science (TEMBS) promoted understanding by supporting the generation of more scientifically accurate models of chemical equilibrium. Secondly, there was a significant improvement in test results of students who received instruction in a traditional form first and then interacted with simulations compared with students who interacted with simulations first and then received traditional instruction. According to the surveys, students in both classes listed teacher discussions in class as one of the three most important contributions to their learning. An implication of this study for science educators and educational technologists is that computer simulations such as TEMBS simulation which utilize multiple
ii representations including a dynamic analogy can assist students in their understanding of abstract concepts such as Le Chatelier’s principle and can be more effective if introduced after a full discussion of the concept and notes.
iii PREFACE
The University of British Columbia, Office of Research Services and Administration,
Behavioral Research Ethics Board has approved this research. The approval number of the certificate is B05-0230.
The Pilot study that is reported in this research has been published as a case study in an article titled, “How Computer Simulations Can Assist Model Generation In Students:
Providing an Adaptable Structure to Guide Student Learning” (Sprague, Trey, Pillay & Khan,
2004). The case study in this article reports the findings from the Pilot Study carried out in two of my Chemistry 12 classes.
iv TABLE OF CONTENTS
Abstract ...... ii
Preface ...... iv
Table of Contents...... v
List of Tables ...... viii
List of Figures ...... ix
Acknowledgements ...... x
Chapter One: Introduction...... 1
Overview of the Research...... 1 Research Hypotheses ...... 4
Chapter Two: Theoretical Framework and Review of Related Literature...... 9
Theoretical Framework: Model-based Inquiry ...... 9 Literature Review ...... 17 Possible Sources of Student Misconceptions in Chemistry ...... 17 Misconceptions in Chemical Equilibrium...... 20 Teaching Strategies to Address Student Conceptions ...... 31 The Role of Computer Simulations in addressing Student Misconceptions...... 39 A Dynamic Analogy View of TEMBS Simulation ...... 50 Sequence of Instruction and Learning Cycle ...... 53 Implications for Research...... 57
Chapter Three: Methodology ...... 59
Preliminary Research...... 59 Research Design...... 63 Classroom Context ...... 63 Participants ...... 63 Research Methods and Procedures...... 65 Data Sources...... 68 Description of the Instructional Sequence...... 73 TEMBS Study Data Analysis ...... 75
v Quantitative Data ...... 75 Qualitative Data...... 76
Reliability of the Data...... 77 Ethical Considerations ...... 79 Protection of Privacy/Confidentiality/Anonymity ...... 79 Consent/Assent ...... 80
Chapter Four: Results ...... 83
Chapter Five: Conclusion and Implications for Teaching ...... 98
Bibliography ...... 104
Appendices...... 110
Appendix A: Principal Letter ...... 110
Appendix B i: Parent Letter ...... 113
Appendix B ii: Parent Consent Form...... 115
Appendix C i: Student Participation Invitation...... 119
Appendix C ii: Student Consent Form...... 121
Appendix D: TEMBS Research Plan 2005...... 125
Appendix E: Equilibrium Project Outline...... 128
Appendix F i: Equilibrium Pre-test...... 129
Appendix F ii: Equilibrium Mid-Test ...... 133
Appendix F iii: Equilibrium Post-test ...... 139
Appendix G i: Interview Consent...... 144
Appendix G ii: Interview Questions...... 147
Appendix H i: Student Survey Consent...... 148
Appendix H ii: Survey #1...... 150
Appendix H iii: Survey #2...... 151
Appendix I i: Simulation Activity # 1...... 155
Appendix J i: Pilot Study Pre-test...... 161
Appendix L: Equilibrium Project Photographs...... 170
vi Appendix M: Glossary ...... 172
Appendix N: UBC Research Ethics Board Approval...... 173
Appendix O: School District 36 Approval ...... 174
vii LIST OF TABLES
Table 1: Problems identified in the Language in Textbooks leading to Alternative Conceptions (Stieff & Wilkensky, 2002)...... 28
Table 2: Pilot Study Research Plan for the Two Chemistry 12 Classes...... 61
Table 3: Thesis Research Plan with Two Classes of Chemistry 12 Students...... 66
Table 4: Equilibrium Pre-test Analysis ...... 84
Table 5: Equilibrium Mid-Test Analysis ...... 84
Table 6: Equilibrium Post-Test Analysis ...... 85
Table 7: Analysis of Equilibrium Survey 1...... 86
Table 8: Analysis of Survey 2 Part 1 ...... 87
viii LIST OF FIGURES
Figure 1: Screenshot of E-Chem...... 41
Figure 2: Screenshort of 4M:CHEM...... 44
Figure 3: Screenshot of NetLogo...... 46
Figure 4: The TEMBS Simulation with the Molecular and Description View...... 49
Figure 5: The TEMBS Simulation with the Analogy and Prediction Mechanism...... 51
Figure 6: Screenshot of Davidson Simulation ...... 60
ix ACKNOWLEDGEMENTS
I offer my enduring gratitude to my colleagues and administration for their guidance and support. My sincere thanks to my Chemistry 12 students for their enthusiasm and participation.
I would like to thank Dr. Samia Khan for her extensive feedback. Her knowledge on the topic was indispensable. I would also like to thank Dr. Stephen Petrina for being part of the committee; his words of motivation and assistance provided were helpful as I was working on my thesis. I also thank Dr. S. Gerofsky for her feedback and her helpful comments.
Finally, I would like to thank my family for their continuous support and encouragement.
x CHAPTER ONE
INTRODUCTION
Overview of the Research
In this research, I examine student understanding of one of the most difficult topics in the
British Columbia (BC) Chemistry 12 curriculum, Chemical Equilibrium and the application of Le
Chatelier’s Principle to equilibrium systems (Science IRP, 2005). A reaction is said to be at equilibrium when the rate at which reactants are used is equal to the rate at which products are produced. This principle is difficult to understand because students are unable to see its applications at the microscopic level. Chemical equilibrium is the central topic in the curriculum as it develops the understanding required for the next three units in the curriculum, acids & bases, solubility equilibrium, and oxidation and reduction. “Le Chatelier’s principle states that if a system at equilibrium is subjected to a stress, (such as changes in temperature, pressure, volume and concentration) the equilibrium is shifted in the direction that tends to relieve the stress” (Holt,
Rinehart & Winston, 2002, p. 562). Taught in the Chemical Equilibrium unit of the Chemistry 12 curriculum, Le Chatelier’s principle is the central concept in the curriculum that is addressed in the solubility equilibrium, acid-base equilibrium and in the oxidation and reduction unit.
Many students have difficulty understanding concepts in chemistry because they are not able to make observations at the microscopic and symbolic levels (Nakleh, 1992). While students are able to make observations at the macroscopic level (e.g., change in color or a lighted splint extinguished with a pop sound), they are not able to understand why because they are not able to actually see the arrangement and motion of molecules, atoms or subatomic particles (Wu Krajcik, &
1 Soloway, 2001). Many students struggle to learn chemistry and often face difficulties understanding the abstract concepts involved in molecular interactions (Nakleh, 1992).
Since most of chemistry instruction tends to involve a more traditional method including labs and demonstrations, it may be possible that many high school students’ difficulties in understanding emanate from not constructing appropriate understandings of important chemical concepts from their earlier pre-high school studies of chemistry (Nakleh, 1992). “Traditional chemistry instruction” tends to be comprised of lecture, note taking, labs, and demonstration. As a chemistry teacher, I find that the level of enthusiasm is much higher when more technology-based instruction is used in the classroom. Students are also more engaged when they work on a project as a group. By working in groups and utilizing technology, there is an opportunity for the students to generate different viewpoints, identify misconceptions and find ways of addressing these misconceptions. However, students may also generate misconceptions as a group.
Chemistry education in this province can be potentially improved if we can help students better understand difficult abstract concepts such as Le Chatelier’s Principle. Digital technology may be able to support this goal.
The study was based on the following research questions:
(1) How can computer simulations that have multiple representations (e.g., TEMBS
simulations) contribute to student understanding of difficult chemistry concepts, such as Le
Chatelier’s Principle?
(2) What is the most effective sequence of instruction for improving student achievement in
chemistry 12? Is there a difference in students’ achievement between: a) traditional
2 instruction preceding computer simulation or b) computer simulation preceding traditional
instruction?
Traditional forms of chemistry instruction that utilize textbooks as the major source of content delivery do not always engage students in evaluating physical or mental models (Khan,
2007; Ozmen, 2004). Even after years of chemistry instruction, many students do not always have an accurate mental image of molecular structures and have alternate conceptions of substances at a molecular level (Coll & Treagust, 2003; Khan, 2007; Nicoll, 2003; Teichart & Stacy, 2002).
Model-based teaching strategies, on the other hand, involve students in a dialogic form of interaction with others to challenge their mental models of the way things work (Khan, 2007). The computer simulation (TEMBS) used in this study is based on a model-based teaching, and principles, such as the use of a computer-based analogy (Khan, 2007 – The TICL study). While methods of teaching chemistry with computer simulations have been reported (Colella, 2000;
Kozma, 2000; Krajcik, & Soloway, 2001; Steiff, & Wilensky, 2003), we currently do not know the optimal sequence of instruction to support students’ understanding of chemistry concepts.
As described in the Terminology section and Chapter 3, the computer simulation used in this study, the TEMBS simulation, was based on an established learning theory framework called the GEM cycle model based learning. This study helps identify how computer simulations with multiple representations can be incorporated into the curriculum and when they are most effectively used for instruction. This study supports other research on the TEMBS simulations
(Khan & Chan, 2010; Khan, 2007; Trey & Khan, 2007) and research on similar simulations that
3 utilize multiple representations (Colella, 2000; Khan, 2008; Kozma, 2000; Piburn, 2005; Steiff &
Wilensky, 2003; Wu & Shah, 2004) .
Simulations alone will not help explain concepts, and the purpose of this research is to provide empirical insight into the sequencing of instruction. Will a class that receives traditional instruction prior to interaction with the simulation perform better than a class that uses the simulation before traditional instruction? Traditional instruction first may have an advantage of preparing for a stronger grasp of the theoretical background on the concept, which could then be reinforced through observations of a simulation. Computer simulations can be effective in addressing misconceptions and improving students’ understanding of abstract concepts, but their use in a sequence of instruction is uncertain.
Research Hypotheses
Computer simulations promote model-based learning and improve students’ understandings. In this case, simulations should improve understandings of Le Chatelier’s principle because students will be able to observe changes at the molecular level (Khan, 2002).
Students who will receive traditional forms of instruction first and then use computer simulations will have higher achievement than students who use simulations first and then receive a traditional form of instruction, because students’ prior knowledge base is strengthened after receiving traditional instruction and interaction with the simulation then allows them to further generate, evaluate and modify any misconceptions. Traditional forms of instruction strengthen students’ prior knowledge base because through lectures and discussions in class, students learn the theories
4 and ideas related to the concept. They may then be able to link the new theories to ones they may have learned in the past.
Assumptions
This study assumed that the students had partial or limited prior knowledge on chemical equilibrium, therefore the students taking the course for the second time were included, but their scores were not considered for research purposes. It was assumed that students had no prior knowledge of computer simulations. It was also assumed that the simulations and instruments designed for the study were valid and appropriate for purposes of the research.
Limitations
One of the limitations of this research may be that students talked or discussed questions with their friends in the other class involved in the study. Two different versions of the test were made. Many students were technologically quite advanced with computers so they may have used simulations before even if it was not the same topic. This may have given these students an advantage over other students in terms of operating the program.
There were some perceived risks with respect to the use of audio taped data. When using audio data, confidentiality cannot be guaranteed; as the researcher may recognize voices of some students. Informed consent forms were obtained from parents and students prior to any audiotaping. Students who did not consent to participation had their voices erased at the end of the course after grades were assigned. Another limitation of the study was the relatively small sample size (n=46) for the interaction with the simulations.
5
Terminology
GEM Cycle: three phases of model construction that are iterative:
1. Generate: Generate a mental model based on prior knowledge and current information
2. Evaluate: Evaluate the model's effectiveness at explaining new information
3. Modify: If the current model does not explain all observations, modify the model
Preconceptions and Misconceptions: To clarify the difference, preconceptions (alternate conceptions) are ideas that are developed without having any prior knowledge of the subject and may not necessarily be wrong. Misconceptions are student ideas or views that may not be consistent with the scientific models. Misconceptions cannot only be attributed to the students, but may also be caused by inappropriate teaching methods and materials (Barke, Hazari &
Yitbarek, 2009).
Technology-Enhanced Model-Based Science (TEMBS): TEMBS refers generally to a project conducted under the direction of Dr. Samia Khan and specifically to computer simulations to enhance students’ understanding (e.g., chemical equilibrium and Le Chatelier’s Principle). TEMBS simulations are designed to facilitate model construction, evaluation, and prediction.
Traditional Instruction Method: This included lecture, discussion, labs, and demonstrations.
This is part of the normal process of instruction. Simulations were not considered part of this method. The lecture sessions were not limited to note-taking and listening to the teacher. There were interactive discussions taking place between the teacher and the students. The teacher took an inquiry approach during the lectures, asking students questions frequently. In this research
6 there was no distinction between lecture and labs. Traditional instruction included lectures, labs and demonstrations.
Summary
Chemical Equilibrium and the application of Le Chatelier’s principle is an abstract concept and one of the most difficult topics in the British Columbia (BC) Chemistry 12 curriculum. Many students have difficulty understanding abstract concepts, like chemical equilibrium, in chemistry because they are not able to make observations at the microscopic and symbolic levels. In this research, I examine how computer simulations can help to improve students’ understanding of the concept of chemical equilibrium. My research questions are: (1) How can computer simulations that have multiple representations (e.g., TEMBS simulations) contribute to student understanding of difficult chemistry concepts, such as Le Chatelier’s Principle? (2) What is the most effective sequence of instruction for improving student achievement in chemistry 12? Is there a difference in students’ achievement between: a) traditional instruction preceding computer simulation or b) computer simulation preceding traditional instruction? My research hypotheses is that students who will receive traditional forms of instruction first and then use computer simulations will have higher achievement than students who use simulations first and then receive a traditional form of instruction. In this study, I assumed that students had no prior knowledge of computer simulations and the instruments designed for the study were valid and appropriate for purposes of the research.
In this chapter I introduced the purpose of the research, the research questions, the research hypotheses, assumptions, limitations and important terminology. In Chapter two I discuss the
7 theoretical framework and review related literature. In Chapter three I discuss the methodology.
This chapter includes preliminary research, research design of this study, classroom context, participants, research procedure, data sources, a description of the instructional sequence, a description of the data analysis, reliability of the data, validity of the research and ethical considerations. In Chapter four I summarize the findings of this study. In Chapter five I state conclusions, recommendations for further research, and implications for teaching.
8 CHAPTER TWO
THEORETICAL FRAMEWORK AND REVIEW OF RELATED LITERATURE
THEORETICAL FRAMEWORK: MODEL-BASED INQUIRY
The theoretical framework is based upon model-based inquiry, a theory which suggests that students can learn abstract concepts while engaged in a form of inquiry (Khan, 2007). Models are representations of the observed and unobserved phenomena that lead one to make certain assumptions or conclusions (Khan, 2007). Mental models are characteristic of an individual’s cognitive interpretation of a concept (Johnson-Laird, 1983; Norman, 1983). Mental models are
“structural analogs of real-world or imagined situations, such as a cat being on a mat or a unicorn being in the forest” (Nersessian, 1992, p. 9). Model construction is promoted by constructing, critiquing, modifying, and expressing one’s mental model through inquiry (Clement, 1989;
Nersessian, 2002). A source of literature on mental models suggests that we “construct internal cognitive representations, or ‘mental models’ as we interact with our environment, artifacts of technology, and others” (Khan, 2005, p. 2).
Model-based inquiry is a dynamic learning cycle that leads to a change in one’s mental models while inquiring about phenomena (Khan, 2007). Mental models can be expressed, shared with others and enriched in the context of teacher-guided student activities (Boulter, Buckley, &
Walkington, 2001; Khan, 2007; Windschitl, 2004). Teachers use model-based teaching to enhance students’ conceptual understanding of phenomena in science (Khan, 2007). One such model-based teaching approach is known as GEM. The GEM cycle approach is a pattern of teaching
9 characterized by generate, evaluate, and modify (Khan, 2005; Khan, 2007). GEM fosters model- based learning in four steps: (1) the teacher identifies information that can be misleading or lead to alternate conceptions; (2) the students generate hypotheses and the teacher provides means of instruction in the classroom in order to address the alternate conceptions or misconceptions that may arise; (3) students evaluate preconceptions and misconceptions through inquiry-based activities in the classroom, including those involving computer simulations; (4) teachers encourage students to modify their preconceptions, reconstruct their understanding of concepts in chemistry and reduce misconceptions.
The construction of models in Chemistry can play a central role in the growth of chemical knowledge. Students come into the classroom with their own personal and unique understanding of scientific models built through their life experiences. These understandings may not be scientifically correct and can give rise to alternative conceptions. Clement and Oviedo (2003) carried out a study on a strategy based on model-based teaching and learning theory. They looked at different teaching strategies that could foster student model construction in large group discussions. The strategy they discussed is called model evolution. The teacher has the opportunity to promote model evolution when the students contribute to a discussion with ideas that are partially compatible with the target of the lesson. The teacher supports the students in repairing the alternative conceptions by fostering small successive episodes of dissatisfaction that originate cycles of model construction and criticism or micro cycles (Clement & Oviedo, 2003).
The data for this study came from videotaped lessons conducted with normal sized middle school classes located in a suburban area. Students’ understanding of human respiration was assessed before and after instruction. The teacher encouraged students to disconfirm, recombine, or
10 restructure their ideas and to generate improved mental models. The teacher-student interactions in this case study had certain patterns that could be interpreted in terms of construction and revision of mental models. The teacher and the students were “co-constructors of knowledge” (Rea-
Ramirez, 1998). Co-construction is the process by which the teacher and the students both contribute ideas to building a model and evaluating it.
Clement and Oviedo’s research team generated a curriculum based on model-based learning and teaching (MBTL) for middle school students on human respiration. The team identified and described different sizes of teacher-student interaction patterns in order to develop new conceptualizations and vocabulary that would be useful in building a model based teaching and learning theory. The study originated from a project where the main goal was to develop a curriculum based on MBTL theory for middle school students on human respiration. Rea-Ramirez
(1998) conducted pilot studies that contributed to the construction of the curriculum. Rea-Ramirez first studied students’ preconceptions through extensive student interviews and conducted a small number of individual pilot tutoring interviews to identify the most efficient teaching tactics. She reported that throughout the instruction the teacher fostered many small cycles of model construction and criticism. Students’ understanding was determined before and after instruction by videotaping the lessons and pre and post assessments. An analysis of the results revealed a significant gain between pre and post assessment scores. Two patterns of learning cycles were observed from the teacher-student interaction. A large pattern was called a macro cycle and a smaller pattern was called micro cycles.
The macro cycle contained several phases such as: Introducing the Topic, Detecting Student
Ideas, Building on Student Ideas, Comparing the Student and the Scientific Models, and Adjusting
11 the Student Model. In the Detecting Student Ideas phase of the macro cycle, the teacher detected the students’ initial ideas. In the Building on Student Ideas phase, the teacher used different kinds of teaching tactics to foster dissatisfaction and modification until students’ ideas were more compatible with the Scientific Models. In the Comparing the Student and the Scientific Models phase, the teacher showed the students an animation that contained the target model and asked them to compare their ideas with the scientific model. In the Adjusting the Student Model phase of the macro cycle, the teacher asked the students to compare their final understanding with their initial ideas. The micro cycles constituted a finer level of cycling that occurred during the Building on Student Ideas phase of the macro cycle.
A micro cycle is a process in which the teacher introduces dissatisfaction and stimulates students to examine and modify an element inside of their models (Clement & Oviedo, 2003). In this process the teacher first asks for students’ ideas, detects a preconception and asks the students to describe the idea. Secondly, the teacher introduces a teaching tactic (such as a discrepant question or event) that generates mild or strong dissatisfaction. Lastly, the teacher uses another teacher tactic to foster modification by encouraging them to restructure, tune or adjust their ideas. This process of modification was defined as model evolution. Model evolution is a process by which the students conduct two or more rounds of modifications in their model. These teaching strategies can be useful to help teachers deal with multiple simultaneous misconceptions. The teacher, after listening and using students’ ideas as the foundation for the instruction, could use the co-construction mode involved with micro cycles to work with students’ alternative conceptions
(Clement & Oviedo, 2003).
12 A study by Khan (2005) explored teacher-designed strategies and the influence of these strategies along with an interactive computer tool on student inquiry in an introductory chemistry course. The strategies were designed by a chemistry teacher. The data, classroom observation, rubric and survey, analysis revealed that students’ generated hypotheses, constructed explanation, and solved problems with regularity in chemistry. The pattern of teaching observed was characterized by generate, evaluate, and modify or GEM cycle. The students interacted with
Chemland software which is a set of multiple, compact, interactive computer modules that are computer representations of simulated lab experiments or molecular processes. For example, in a simulated heat calorimetry experiment, students could change several variables associated with calorimetry, such as selecting the type of compound to place in the calorimetry, the amount of water in the water bath, etc. The teacher then asked students to generate a relationship between molecular weight and boiling point. Some students may respond, “As molecular weight increases, the boiling point increases”. Some students also noted that as temperature increased the vapour pressure also increased. The teacher then asked students to explain why. Some students proposed a “mass model” suggesting that the lower the mass the quicker the vapour pressure would increase.
Still one student remained unconvinced and explained the different rates of vaporization between methanol and ethanol. The students suggested that the molecular structure of ethanol is postulated as having weaker bonds because it is a longer chain. The student proposed that one of the hydroxyl ends of the molecule would pull electrons within the chain towards itself, weakening the remaining bonds. The results from the study showed that these teaching strategies promoted student engagement with generating hypotheses, a key facet of scientific inquiry. Three guidance strategies identified were: not correcting students’ initial models; asking students to explain what
13 they thought was happening at the molecular level;, and asking students to compare molecular compounds, including compounds that did not appear to follow initial trends. The study found that a combination of factors contributed to successful student engagement, including the teacher’s interactive role in the classroom and the use of specific teacher guidance strategies to enhance student engagement with generating, evaluating, and modifying hypotheses (Khan, 2005).
Model-based learning encourages students to identify their preconceptions. Student preconceptions (ideas or beliefs that students have acquired through their life experiences, formal or informal instruction before instruction in class), and students’ abilities to integrate ideas are both important in developing robust conceptual understanding (Teichart & Stacy, 2002).
Preconceptions become important when students are able to integrate them into a more complete understanding and integration of new concepts can be done more readily when students’ initial ideas are considered by the teacher (Teichart & Stacy, 2002). When students come into the classroom they bring with them their everyday experiences and ideas acquired both formally and informally. The teacher must be aware that these preconceptions may or may not be scientifically correct, and students may or may not integrate this prior knowledge with new information gained in the classroom. The GEM learning process involves the restructuring and reorganization of knowledge based upon students’ prior knowledge. If students’ initial ideas are not addressed in class, they may remain unchanged and continue to exist even after instruction. Preconceptions, if correct, can be used to build further instruction. However preconceptions whether they are correct or not, must be addressed in the classroom instruction if students are to build scientifically accurate conceptual understandings (Teichart & Stacy, 2002).
14 Khan (2007), in her research with chemistry students on model-based teaching, revealed that teachers co-constructing mental models with students is an interactive form of instruction involving students’ generation and evaluation of their mental-models, the GEM approach. An undergraduate chemistry class was involved in this study and data were collected from classroom observations, student surveys, and in-depth problem solving sessions with the instructor and students. The teacher-student interaction revealed a cyclic pattern in which students generated, evaluated, and modified (GEM) hypotheses throughout the course. Students from the study were found to progressively generate relationships expressing in the form of analogy, drawings, and peer dialogue. The main finding in this research was a distinctive mode of teacher-students interaction identified as the GEM cycle approach. The analysis of student construction via a GEM approach contributes to a broader theoretical discussion on the reasoning processes that are part of inquiry, involving the construction and revision of mental models. In the inquiry-based classroom, students enriched their models of intermolecular forces through a simultaneous and ongoing process of generating, evaluating, and modifying hypotheses. The study suggested that both modeling and inquiry facilitate the development and revision of abstract concepts.
Khan (2008) investigated how a teacher fostered conceptual understanding of molecules and the forces that exist between them without directly telling them. The teacher’s strategy was to have students develop and express mental models of molecular structures that would help them explain laboratory findings. The students were guided to construct their own models. The approach involved the teacher encouraging students to express their mental models, enriching their models and then asking students to test their model. The teacher first asked students to predict their laboratory results and then asked them for their reasons for the predictions in order to assess
15 students’ prior knowledge. Once students’ mental models were expressed, the teacher then sought to enrich students’ models by co-constructing connections to more variables, such as pressure and its effect on the boiling point of molecules. Finally, students expressed models of molecules and the forces that exist between them appeared to change significantly as they were tested. This stage involved the teacher engaging students with further questioning to encourage them to further explain lab information and perhaps reconsider their initial models of molecular structures (Khan,
2008).
A GEM instructional approach was implemented into the instructional sequence in this research, and a simulation designed by Khan’s research team was also incorporated. The simulation called Technology-Enhanced Model-Based Science (TEMBS) is a computer simulation designed to promote students’ understanding of chemical equilibrium and Le Chatelier’s Principle.
The simulation includes features such as the prediction mode, analogy view, molecular view and symbolic representations. The multiple representations in this simulation encouraged students to generate their mental models on chemical equilibrium. The molecular view allowed students to visualize the interaction of the molecules. The scale analogy view allows students to relate their mental models on chemical equilibrium to the real-world.
16 LITERATURE REVIEW OF CHEMISTRY EDUCATION AND TECHNOLOGY
To help address my first research question, How can computer simulations that have multiple representations (e.g., TEMBS simulations) contribute to student understanding of difficult chemistry concepts, such as Le Chatelier’s Principle?, I will be reviewing the following: (1) Sources of misconceptions in chemistry, (2) Misconceptions pertaining to the chemical equilibrium concept and, (3) Teaching strategies to address student conceptions in chemistry. One of the teaching strategies to address student misconceptions is the integration of computer simulations with multiple representations. Therefore, also included in this literature review is: (4) The role of computer simulations in addressing student misconceptions and improving student understanding of abstract concepts, (5) The TEMBS
Simulation. TEMBS simulation is explicitly developed based on model-based teaching and learning theory and incorporating multiple digital representations. To address the second research question, What is the most effective sequence of instruction for improving student achievement in chemistry 12? Is there a difference in students’ achievement between: a) traditional instruction preceding computer simulation or b) computer simulation preceding traditional instruction?, I reviewed literature on: (6) The Issue of Sequence of Instruction and
Learning Cycles.
Possible Sources of Student Misconceptions in Chemistry
Two terms referenced throughout this research study a number of times are preconceptions and misconceptions. To clarify the difference, preconceptions (alternate conceptions) are ideas that are developed without having any prior knowledge of the subject
17 and may not necessarily be wrong (Barke, Hazari & Yitbarek, 2009). Misconceptions are student ideas or views that may not be consistent with the scientific models.
Misconceptions cannot be solely attributed to the students but caused primarily by inappropriate teaching methods and materials (Barke, Hazari & Yitbarek, 2009).
When students build their own concepts, their constructions of a chemical concept may differ from the one that the teacher holds or attempts to present (Nakleh, 1992). These misconceptions tend to interfere with the student’s learning as the student connects new information to a cognitive structure that already holds inappropriate knowledge. Misconceptions may arise as a result of the following: (1) Language used in textbooks, (2) Traditional forms of instruction, (3) Teachers’ lack of knowledge on students’ prior understanding of concepts and, (4)
Informal prior knowledge from everyday experiences.
In order to apply the skills and knowledge in Chemistry at post secondary level, high school students need to understand chemical processes at the molecular level (Spier-Dance, Khan &
Dance, 2005). Their study on textbooks and student understanding in introductory undergraduate chemistry found that in-depth theoretical explanations are often left out in textbooks and replaced by non-explanatory memory aids in chemistry, potentially giving rise to alternate conceptions. For example, the following passage from a chemistry textbook, “At equilibrium the net effect is zero because there is no net reaction” may lead to the alternate conception, “At equilibrium no reaction is taking place”. A non-explanatory memory aid in chemistry, for example, is ‘LEO the Lion says
GER’ meaning loss of electrons is oxidation and gain of electrons is reduction. According to Spier-
Dance, Khan and Dance (2005) textbooks also often fail to address alternate conceptions in chemistry by providing overly simplified but scientifically acceptable conceptual explanations. The
18 authors have suggested that to overcome this situation, teachers and authors need to address students’ prior conceptions and their difficulties in understanding chemistry when using textbooks.
Research indicates that after receiving traditional chemistry instruction, such as instruction relying on textbook reading, lectures and labs, students continue to lack deep conceptual understanding and are unable to integrate their ideas into applying those concepts to other relevant ideas in chemistry (Nakleh, 1992). Researchers in the chemistry education community also find that although students may be successful in solving mathematical or algorithmic exercises, it may not necessarily indicate that they have mastered the scientific concepts required to solve those problems (Nakleh, 1992). Instructors, textbooks and tests or assessments often overly emphasize algorithmic exercises; learning algorithms in chemistry, however, may not ensure that students have complete understanding of the concepts (Teichart & Stacy, 2002). Traditional forms of instruction, such as reading textbooks, lectures and labs may be a source of misconceptions.
There are two sources students use to construct their concepts: public knowledge, as presented in texts and lectures, and informal prior knowledge from everyday experiences, peers, parents, commercial products and the common meanings of scientific terms (Nakleh, 1993). The common meanings of scientific terms refer to students’ confusion over terms used in everyday lives, such as ‘mental equilibrium’ or ‘balances’ with ‘chemical equilibrium’ in chemistry.
Although such references can be useful in making a concept clear, they may be misleading if not approached appropriately.
Thus some sources of misconceptions are: (1) In-depth theoretical explanations left out and replaced by non-explanatory memory aids in textbooks; (2) Textbooks failing to address students’ prior conceptions; (3) Instructors, textbooks and assessments overly emphasizing that students
19 perform many problem-based algorithmic exercises and not ensuring that students have complete understanding of concepts; (4) Informal prior knowledge from everyday experiences.
Misconceptions in Chemical Equilibrium
The problems associated with understanding chemical equilibrium concepts in particular have been reviewed by a number of authors (Garnet, Garnett, & Hacking, 1995; Griffiths, 1994;
Quilez & Solaz, 1995; Raviolo & Martinez, 2003; Van Driel & Graber, 2002). Chemical equilibrium is taught in most high school chemistry courses. The concept of chemical equilibrium requires students to understand the relationship between several physical variables (e.g., pressure, temperature, concentration), several symbolic expressions (e.g., reaction quotient, equilibrium constant) and the equilibrium position of a chemical reaction. Generally students learn the concept of equilibrium by memorizing definitions and rules for predicting equilibrium position of a chemical reaction based on the physical variables applied to the reaction (Steiff & Wilensky, 2002).
In the Chemistry 12 BC curriculum, students study chemical kinetics before they study the unit on chemical equilibrium. In the chemical kinetics unit, students study the factors that can affect a rate of a reaction, such as temperature, pressure, concentration, surface area, volume and catalyst. In this unit, students look at reactions that proceed in one direction only, that is, reactants forming products. They learn that increasing temperature, concentration of reactants, pressure, surface area and adding a catalyst increases the rate of the forward reaction. The students are briefly introduced to the possibility of certain reactions proceeding in both directions, forward and reverse, but the concept of chemical equilibrium is not introduced yet. When students are
20 introduced to the chemical equilibrium unit, however, they get confused as the entire unit is based on reactions that tend to proceed in both directions, reactants to products and products to reactants. A common misconception students may have is that in the chemical kinetics unit students have learned that increasing temperature increases the ‘rate’ of the reaction whether the forward reaction is endothermic (energy needs to be absorbed by the reactants) or exothermic
(energy is released as the products are formed) whereas in the chemical equilibrium unit, for reactions that can proceed both ways students now need to consider the ‘rates’ (forward or reverse) of the reactions. They need to understand that for reversible reactions, increasing temperature still does increase both forward and reverse rates but increases the endothermic reaction more and as a result the equilibrium shifts towards left or right (producing more reactants or products) depending on which side the energy needs to be absorbed. In the following example,
N2 (g) + 3H2 (g) ⇔ 2NH3 (g) + Energy increasing temperature will favor the reverse reaction. The product concentration will decrease and reactant concentration will increase. Students are able to understand, with repeated explanations and examples, how temperature affects reversible reactions or a reaction at equilibrium, but most of the time they fail to understand the immediate effect of increasing temperature, which is that both the rates increase. It is important that students understand that an increase in temperature increases the rate of the reaction, both forward and reverse rates, because the kinetic energy of the molecules increases, the molecules start moving faster and more collisions are taking place. They also need to understand that for a reversible reaction the rate of the endothermic reaction increases more and therefore would shift to produce either more reactants or products. For example, in the reaction mentioned earlier, an increase in temperature would increase the production of reactants
21 and products, but would increase reactants more as the product, ammonia, would absorb the heat and form more reactants.
In introductory chemistry lessons in grades 8 to 11, chemical reactions are given as proceeding to completion in one direction whereas in chemical equilibrium, studied in grade 12, three basic ideas are considered: incomplete reaction, reversibility and dynamics. Students find these three concepts difficult to understand since they first start with reactions that proceed in one direction and that the reaction stops when one of the reactants is used up, for example, calcium carbonate reacting with hydrochloric acid to produce calcium chloride, water and carbon dioxide gas. As soon as either one of the reactants, calcium carbonate or hydrochloric acid is used up the reaction stops. In grade 12, however, students learn that certain reactions may not go to completion but reach a state of equilibrium. As a result students face a number of conflicts when dealing with chemical equilibrium reactions (Quilez, 2004).
Another misconception students have regarding chemical equilibrium is that they incorrectly assume that when equilibrium is reached, the reaction stops. Students are not able to understand the dynamic nature of chemical equilibrium; that is, forward and reverse reactions continue to take place when equilibrium is attained. Since the rate of forward and reverse reactions are equal at equilibrium, the concentrations of reactants and products become constant. The rate becomes equal means that, for example, if the rate of the forward reaction is 0.05mol/s then the rate of the reverse reaction would also be 0.05mol/s. The concentrations become constant means that if the concentration of a reactant at equilibrium is
0.2mol/L and the concentration of a product is 0.35mol/L, then their concentrations do not change. Also, the stoichiometry of the reaction remains unchanged; in other words, the ratio
22 of the reactants to products does not change. Rather, it is only the rate at which reactants are used that is equal to the rate at which products are produced. When students get involved in topics that are abstract, due to their complexity it is often possible to address themes in a cut-and-dry manner. Despite competent and qualified teachers, occasionally questions remain open and problems are not really solved for a complete understanding (Barke, Hazari,
A., & Yitbarek, 2009). There are three levels of thought: the macro and tangible, the sub- micro atomic and molecular, and the representational use of symbols and mathematics
(Johnstone, 2000). According to Johnstone (2000), “Macro” refers to what can be seen, touched and smelled, “Sub-micro” refers to atoms, ions, molecules, chemical structures and
“Representational” refers to symbols, formulae, equations, molarities, tables and graphs.
Gabel (1999) pointed out that teachers are likely to go from the macro level directly to the representational level and students may have difficulty relating to the concept. According to
Gabel (1999), the primary barrier to understanding chemistry is not the existence of the three levels of representing matter but that chemistry introduction occurs predominantly on the most abstract level, the symbolic level.
Gussarsky and Gorodetsky (1990) probed grade 12 chemistry students’ understanding of chemical equilibrium. Their study found that students did not perceive the equilibrium mixture as an entity but rather treated each side of the chemical equation independently. Students, therefore, may have a compartmentalized view when applying Le Chatelier’s Principle; for example, when a stress such as increasing pressure is applied to an equilibrium system, students fail to understand that the change affects both reactants and products. They fail to understand that reactants and products are all together under a closed system and are both affected by the change. As suggested
23 earlier, students also failed to understand the dynamic nature of equilibrium. According to
Gussarsky and Gorodetsky (1990), students are not able to understand that when a reaction has reached equilibrium, the forward and reverse reactions continue to take place at an equal rate.
Students assume that since all macroscopic observable properties such as colour, temperature, concentration, and pressure become constant, the reaction has stopped. The authors also noted that students confused everyday meanings for equilibrium with chemical equilibrium. Students interpreted “equilibrium” as a physical balance like riding a bicycle, or mental balance, or balance in the sense of weighing. In all of these everyday uses, the state of equilibrium is presented as a static, balanced condition. They also found that equilibrium problems are often highly abstract and the mathematical calculations can be done by rote. Mathematical calculations related to chemical equilibrium can be learned through repeated exercises and constant practice. Students might achieve good grades on tests, but it may not necessarily indicate a clear understanding of the concept.
In an interview based study with Australian high school students, students were required to explain and graph the changes that could occur in the rates and the concentrations during a chemical equilibrium reaction between nitric oxide and chlorine to form nitrosyl chloride (Nakleh, 1992).
The students’ responses revealed both misconceptions in the particulate nature of matter and the dynamic nature of chemical reactions. As suggested in other research, most of the students thought that the concentrations of the reactants equal the concentrations of the products at equilibrium.
This misconception may be explained by the students’ lack of understanding of how the coefficients in a chemical equation are used in the equilibrium expression. For example, when the ratio of reactants to products is one to one, then students assume that when the concentrations are equal then the reaction is at equilibrium. More than 50% of the students also expressed the belief
24 that when equilibrium was disturbed, the initial result was that the rate of the forward reaction would be increased and that the rate of the reverse reaction would be decreased. The rates of forward and reverse reactions, however, are dependent on whether the forward reaction is exothermic or endothermic and what stresses (change in temperature, pressure, concentrations, etc) are applied. The students therefore exhibited a poor understanding of the dynamics of an equilibrium system (Nakleh, 1992). The students also failed to understand that when a stress is applied either the forward or reverse rate increases but do not decrease the opposing reaction. In order to have a robust understanding of the chemical equilibrium concept students need to understand that either the forward or reverse rate would increase either gradually or instantly and then the rate would decrease as the opposing rate increases until they become equal, at which time the reaction would have achieved equilibrium.
Kozma, Russell, Johnston and Dershimer (1990) studied first year college students’ understanding of chemical equilibrium. They used students' verbal commentary and their written answers on Le Chatelier’s problems to identify two groups of students who had conceptions of equilibrium that were not consistent with the scientific conception. One group of students understood that equilibrium involves a dynamic exchange, while the concentrations are held constant but could not use that knowledge to solve Le Chatelier’s problems. Le Chatelier’s principle states that when a system at equilibrium is subjected to a stress (change in temperature, pressure, concentration, etc), the system will tend to counteract that stress and shift in the direction in order to oppose that stress. Le Chatelier’s principle is the central concept in the chemical equilibrium unit and is constantly addressed in explaining shifts in equilibrium. The other group could solve Le Chatelier problems but thought that equilibrium meant that there was no
25 dynamic interchange between the components of the system and that it only occurred when the system was stressed. This study indicated that the first group of students had difficulty processing and applying the concept they seemed to know. It may be possible that these facts were memorized without any understanding and therefore they were not able to solve Le
Chatelier’s problems. The second group of students may also have memorized solutions to typical
Le Chatelier’s problems through repeated exercises and were therefore able to solve problems without understanding the concept.
Students misconceive equilibrium as a static process and therefore have difficulty in defining equilibrium (Steiff & Wilensky, 2002). Recall that a chemical reaction is at equilibrium when the rate at which reactants are converted to products is equal to the rate at which products are converted to reactants. Therefore, at equilibrium the concentrations of reactants and products stay constant at the macroscopic level; on the sub micro-level, however, forward and reverse reactions continue to take place such that the conversion of reactants to products and products to reactants are taking place at an equal rate. Students are able to observe this appearance of constancy as the colour of the mixture, temperature of the mixture and pressure within the container holding the mixture stay constant. Students are not able to observe the dynamic nature of equilibrium at the molecular level since they can only observe changes at the macroscopic level, which are observable, such as changes in colour. Some students may remember these facts (e.g., macroscopic properties become constant but microscopic changes continue to take place; forward and reverse reactions continue to take place at an equal rate) from their textbooks or from lectures in class, but may not be able to apply these facts to problem solving.
26 During their three-part 90 minute interviews with six undergraduate science majors, Steiff and Wilensky (2002) found that participants in their study of the potential impact of a novel modeling and simulation package, ChemLogo, on students’ understanding of chemistry presented inconsistencies in their conceptual understanding when they were asked to describe the equilibrium state of specific chemical reactions. When the students were asked traditional chemistry questions, it was clear to the authors that they were reasoning by rote recall or through training and practice.
One of the misconceptions that arose in the study among student participants is that they looked at the mole ratio in a reaction such as: 2NO2 ⇔ N2O4 , and assumed that there will always be more reactants than products. The students made the assumption that the ratio indicates the relative concentrations of the reactants to products. A molecular view of this reaction may show one molecule of the product for every two molecules of the reactant. The students may count the molecules and consider the numbers to indicate the concentrations. The numbers indicate the ratio of reactants to products. The number of molecules does not represent the concentrations. The concentration is dependent on the individual mass of the atoms and not the number of atoms. This
“counting” of molecules indicates a dependence on the symbolic representation for their explanations (Steiff & Wilensky, 2002). A summary of their findings is listed in Table 1.
27
Table 1: Problems identified in the Language in Textbooks leading to Alternative Conceptions (Stieff & Wilkensky, 2002)
Problems Identified in the Language in Alternative Conception Textbooks 1. At equilibrium the net effect is zero because At equilibrium no reaction is taking place. there is no net reaction. 2. For temperatures below 11000C, the higher Rate of reaction means the same as extent of the pressure is, the higher will be the conversion reaction. percentage; the time interval to attain the equilibrium will also be higher. 3. There is a general rule that helps us to The effect of imposing a constraint, such as predict the direction in which an equilibrium changing temperature or pressure on a reaction will move when a change in system in equilibrium is to cause a change concentration, pressure, volume or temperature in the amounts of substances on one side occurs. The temperature increase shifts the of the equation for the reaction (thus equilibrium in the direction of the endothermic representing a compartmentalized view of reaction. A system pressure increase shifts the equilibrium as somehow involving two equilibrium in the direction of less number of disconnected sides of a reaction. moles.
Learning about chemical equilibrium requires various conceptualizations in order to promote understanding of complex dynamics of transformations of one form of substance to another. When chemical equilibrium is reached, the resulting system reaches a stable state and no observable changes are made. This is seen as two chemical reactions, forward and reverse, that are taking place in a closed container at an equal rate. The words reversible chemical reaction can be misleading for high school students as it may contradict the fact that there are two chemical reactions that are occurring (Pedrosa & Dias, 2000).
Textbooks also do not attempt to clarify this misunderstanding and move on to looking at the behaviour of chemical equilibriums when a stress (change in temperature, pressure, or concentration) is applied to the equilibrium. The idea of reversibility is identified in textbooks as
28 (⇔), where the double arrows indicate the reaction is reversible. The double arrows are meant to indicate that there are two reactions occurring in the equilibrium system. The textbooks talk about the reaction instead of the reactions and this can be misleading for the students (Pedrosa & Dias,
2000).
A study by Kousathana and Tsaparlis (2002) compared final upper-secondary school year
(age 17-18) students’ performance on chemical equilibrium problems. Errors made by the students while solving these problems were of two kinds: (1) random errors caused by thoughtlessness, or by an overload of working memory, or by field independence and (2) systematic errors as a result of misconceptions or difficulty in understanding the concept. It was found that the students incorrectly apply Le Chatelier’s principle to chemical equilibrium even when a solid is added to a heterogeneous system or an inert gas is added to a homogeneous system at equilibrium. A heterogeneous system is one where reactants are present in different phases, whereas a homogenous system is one where the reactants are present in the same phase (for example, nitrogen gas and hydrogen gas react to produce ammonia gas). When a solid is added to a heterogeneous system, the equilibrium is not disturbed and no shift occurs since the concentration of the solid does not change. When an inert gas such as helium is added to a homogeneous system, the total pressure increases but it does not change the partial pressure of the reaction gases present.
Therefore the equilibrium position of the reaction system is unaffected and there are no shifts. The students often think that the pressure of the system increases, and they will say how it would increase the concentration of the reactants or products.
Kousathana and Tsaparlis (2002) further identified that students thought an increase in temperature always increases the value of the equilibrium constant. This misconception may have
29 originated from the discussion on reaction kinetics. From reaction kinetics, students learn that an increase in temperature results in an increase in reaction rate leading students to believe that the increase in reaction rate means an increase in amount of products. As a result they assume that the equilibrium constant value also increases. It must be pointed out to students that the increase in temperature does increase the forward and the reverse rates; however, the endothermic reaction is increased more. According to Le Chatelier’s principle, the endothermic reaction whether forward or reverse will absorb the added heat and shift to produce more reactants or products. Thus the value of the equilibrium constant may increase or decrease, depending on whether the forward reaction is endothermic or reverse reaction is endothermic. Kousathana and Tsaparlis (2002) also found the following: (1) Students included the “concentrations” of solids (species outside the phase in which the reaction occurs) in the equilibrium constant expression (2) Failure to correctly predict the direction of the reaction in the case of random initial amounts of reactants and products. This question involves the calculation of the reaction quotient, Q, which they use to compare with the equilibrium constant and depending on whether the value is greater than or less than the equilibrium constant, they predict which way the equilibrium must shift in order to reach equilibrium. If the value of Q is equal to the equilibrium constant than the mixture is already at equilibrium.
Furthermore, (6) The position of equilibrium does not change if equal numbers of moles of a reactant and a product are added to a system, which is at equilibrium. The misconception here might rest with the term equilibrium, which contains the word equal, thus representing chemical equilibrium in terms of a static balance.
Quilez (2004) summarized a number of conflicts students face when dealing with chemical equilibrium. Students 1) often do not discriminate between reactions that go to completion and
30 reversible reactions; 2) may believe that the forward reaction goes to completion before the reverse reaction commences; 3) May fail to distinguish between rate (how fast) and extent (how far); 4)
Often think that the rate of the forward reaction increases with time from the mixing of reactants until the equilibrium is established; 5) fail to understand the dynamic nature of a system in a state of chemical equilibrium (instead many of them hold a static conception, believing that nothing happens and the reaction has stopped); 6) conceptualize equilibrium as oscillating like a pendulum
(reaction proceeding in one direction at a time); 7) hold a compartmentalized view of equilibrium, where they feel a change in variable (temperature, pressure, or concentration) is applied to the reactants only; 8) think that mass and concentration mean the same thing for substances in equilibrium systems; 9) think that the concentrations of the reactants at equilibrium equal the concentrations of the products, and 10) express difficulties in understanding and using many of the terms (e.g., equilibrium, displacement, shift, stress, balanced, and reversible) used in chemical equilibrium lessons.
Teaching Strategies to Address Student Conceptions
Kousathana and Tsaparlis (2002) made the following suggestions for chemistry educators in addressing student misconceptions: (1) That problem solving should take place before conceptual questions since the practice of algorithms can be conflicting with the subsequent concept learning
(2) Particular attention should be paid to the developmental level, working-memory capacity, mental capacity, etc. of students (3) The mental demand on the students to be increased gradually to avoid overloading their working memory; (4) There should be more emphasis on moving away
31 from algorithmic to activities that require higher mental processes. Although conceptual understanding may not be necessary when applied to algorithms, students will be more capable of dealing with more demanding problems with such understanding.
Minstrell (1989) pointed out that classroom instruction should be designed with students’ initial thoughts and reasoning in mind. He made the following suggestions: (1) that every student should be given the opportunity to identify his or her thoughts (2) that written records of initial ideas should be kept and in that way students will be able to see any inconsistencies between what they originally held and the actual concept and (3) that students’ prior conceptions should be clarified during instruction through discussions. For example, in the discussion of bond energies in the Teichart and Stacy (2002) study, the instructor wrote out students’ preconceptions or initial ideas on the board and asked for student feedback. The instructor’s role was to facilitate the discussion with questions like, “What do you mean?” “Why do you think that?” and “Does that agree with what others are saying?” Such critical thinking questions help promote student understanding through explanations. The instructor does not provide correct answers directly, but through prompting and providing challenging contradicting information helps to address misconceptions (Teichart & Stacy, 2002).
Apart from identifying preconceptions teachers should also design instruction to allow students to restructure their prior understanding based on what is taught in class. If students are not given the opportunity to integrate their own ideas with new classroom ideas, they may not know which ideas are appropriate for solving problems (Clement, 1982; Teichart & Stacy, 2002).
Students can be taught a new lesson and how to use the concepts learned from the lesson successfully, provided students are able to compare the newly learned concepts to their prior
32 knowledge. If concepts are tied to certain contexts that students may find not so convincing, then they may never compare them and may overlook any inconsistencies (Teichart & Stacy, 2002).
For example, students may hold the following two ideas simultaneously: (1) Bonds are stable and atoms bond together to reach a more stable state, and (2) bonds store energy, which is released when a bond breaks. Students may find that these two ideas contradict each other: if bonds are stable, they are lower in energy than are unbonded atoms, and it thus requires energy to break bonds (Teichart & Stacy, 2002). Traditional instruction in the form of lecture, labs and textbook readings does not encourage students to form an integrated understanding because it does not require that they compare their ideas. Even though students may hold the two correct conceptions about bonding, if they are not able to integrate the two concepts then they may not be able to see the complete picture that bonds are stable, lower in energy and thus require energy to break
(Teichart & Stacy, 2002).
Question and answering sessions are the most common strategy to determine students’ prior knowledge on a topic, but other diagnostic instruments offer better teaching approaches. These instruments or techniques may include concept mapping, interviews, prediction-observation-explanation, drawings, word association and pencil and paper diagnostic instruments based on multiple-choice items (Peterson & Treagust, 1989; Schmidt,
1997; White & Gunstone, 1992). Although many instructors use multiple-choice tests to evaluate student content knowledge, they are limited in terms of determining students’ reasoning behind them. Many instructors also find that one of the ways that students can assess how well they have understood a concept is how well they can explain the concept to another student (Teichart & Stacy, 2002).
33 Teachers should be provided appropriate training through teacher education programs and workshops so that they can identify their own students’ misconceptions and plan lessons accordingly. Through their training, teachers can help students acquire skills to relate new information to prior knowledge, to make connections from one subject area to another, to relate classroom lessons to everyday experiences, and to become meaningful learners who are able to retain and use this information (Ozmen, 2004; Prawat, 1989). The majority of teachers use teacher-centered teaching strategies to teach science (Lord, 1999; Ozmen, 2004;
Yip, 2001). Students are trained to be good at recalling factual information and rote applications of algorithms in order to be successful in examinations. Traditional teaching strategies, while effective in getting students to learn, memorize and reproduce on the day of examination, are ineffective in helping students understand abstract concepts such as chemical bonding and chemical equilibrium (Westbrook & Marek, 1991).
According to Nakleh (1992), students’ model of learning can be viewed as a cyclic process where new information is compared to prior knowledge and then fed back into the same knowledge base. Students construct cognitive structures that are based on sensible and relevant understandings of the information and phenomena in their world from their own point of view.
These cognitive structures are difficult to deconstruct, as students tend to hold on to their beliefs, therefore it requires strategies that need to be incorporated into instruction to identify these misconceptions and develop ways of addressing these misconceptions.
Alternative conceptions about molecular structures can be reinforced by pictures, models, diagrams, analogies used in textbooks, and a lack of theoretical explanations during class discussions
(Spier-Dance, Khan, & Dance, 2005). Here the role of teacher guidance and explanation is very
34 important in helping students to develop mental models in understanding scientific concepts.
According to Khan (2005), the surveyed students in the study ranked peer discussion at the computer and discussion with their teachers as their top two learning factors out of nine choices.
Nicoll (2001) suggested that teachers should emphasize the relationship between the symbolic, macroscopic, and microscopic worlds of chemistry so that students will develop their own mental models of chemistry concepts accordingly. The symbolic world of chemistry refers to the use of formulae and equations to represent chemical reactions. The macroscopic world of chemistry refers to physical properties of chemicals such as temperature, colour, pressure, etc and the microscopic world refers to changes at the molecular level, which cannot be observed. Studies indicate that teachers were more likely to rely upon low-level questions and give students fewer opportunities to speak if they were less knowledgeable (Valanides, 2000). As a result of high-order questions, students are given more opportunities to talk, allowing them to develop the concepts and have a better understanding (Berquist & Heikkinen, 2000).
Instruction needs to be more concept-based (Nakleh, 1993). There is much emphasis placed on algorithmic exercises and studies have shown that high algorithmic skills do not necessarily mean high conceptual understanding. An effective way to measure how well students have understood a concept is to find out how well they can explain the concept to another student
(Teichart & Stacy, 2002). Like many beginning teachers, students may realize holes in their understanding as they are explaining a concept to someone else. Research indicates that students learn more effectively when they give explanations rather than only receive explanations (Teichart
& Stacy, 2002). According to Webb (1989), conceptual change is more likely to happen when
35 students are “required to explain, elaborate, or defend one’s position to others, as well as to oneself” (Teichart & Stacy, 2002). When students explain concepts to one another, it helps them to clarify their understanding and reorganize knowledge and identify any inconsistencies in their understanding (Teichart & Stacy, 2002). Research has shown that students who explained concepts to themselves or to others performed significantly better than students who did not self- explain (Chi & Bassock, 1989). Further studies have also shown that self-explanation and self- regulation strategies are skills that can be taught and it did improve learning (Teichart & Stacy,
2002). The study showed that students who explained either through training or on their own spent more time studying examples and looking through their texts than non-explainers. Several studies have also shown that self-explanation and self-questioning techniques can be taught in the classroom and has shown to improve learning. Group discussions are an effective way to encourage more students to participate in constructing explanatory answers, especially if they hesitate to respond during class discussions. This would also help to encourage students who do not self-explain at all. Student explanation improves problem solving and helps students understand their texts as they read through it. Self-explanation has been found to be effective in both written and verbal means of communication. It also encourages students to integrate new concepts with prior knowledge as they try to understand what they are learning and how it relates to what they already know (Teichart & Stacy, 2002).
Co-construction and model evolution, as described in the theoretical framework section of this chapter, is a process where teachers guide students to enrich their expressed models of a phenomenon (Khan, 2008). Khan (2008), in her study based on a learning episode with a pair of introductory chemistry students and their chemistry teacher, provided examples of how teachers
36 can guide their students to enrich their mental models by encouraging students to focus on important relationships that make up the model. The study reveals how students can construct relationships between two variables using lab information, how their relationships can become successively more complex to include four variables, and how students are able to reason through conceptually changing material (Khan, 2008). The study shows how the teacher fostered conceptual understanding of molecules and the forces that exist between them, without directly telling students about bonds. This approach is considered different from a “teaching by telling” approach but rather guiding students to construct their own models. The process involved first asking students to make predictions about laboratory results and the reasons for their predictions.
This allowed the teacher to access students’ prior knowledge and to express their thinking about chemistry and reasoning at a molecular level. Once students’ mental models were revealed, the teacher was able to work with the student to enrich their mental model. Secondly, to enrich the students’ mental model, the teacher co-constructed connections to more variables. Asking students to make a prediction affords students the opportunity to express their initial models. The teacher did not correct students’ predictions but added content to their explanations. Students independently constructed relationships and added variables to their models resulting in enriched models.
According to Khan (2007), a cyclical pattern in which students generate, evaluate, and modify (GEM) represents a promising approach towards scientific inquiry, model construction and revision. The generate phase involves students identifying the variables, observing any trends and predicting a relationship between the variables and any trend observed. During the evaluation phase, students are asked to compare, find new information and design a new test. In the
37 modification phase, students are asked to revisit their original relationships and models and solve a new case. In her study of an undergraduate class on their understanding of molecular structures,
Khan (2007) found that according to the survey, students ranked GEM as one of the most effective learning experiences for them. The students enriched their models of molecular structures and developed understanding of intermolecular forces through an ongoing process of generating, evaluating, and modifying.
Therefore student misconceptions may be attributed to inappropriate teaching methods, language used in textbooks and students’ prior knowledge from everyday experiences (Barke,
Hazari & Yitbarek, 2009). Some of the misconceptions identified on the topic of chemical equilibrium are: (1) The concentrations of all species in the reaction mixture are equal at equilibrium; (2) Large values of equilibrium constant imply a very fast reaction; (3) Increasing the temperature of an exothermic reaction would decrease the rate of the forward reaction; (4) The rate of the forward reaction increases with the time from the mixing of the reactants until equilibrium is established; (5) Concentration of reactants equals concentration of products; (6) When a system is at equilibrium and a change is made in the conditions, the rate of the forward reaction increases but the rate of the other reaction decreases and; (7) The rate of the forward and reverse reactions could be affected differently by addition of a catalyst (Barke, Hazari & Yitbarek, 2009).
Some teaching strategies to address student conceptions are (Barke, Hazari & Yitbarek,
2009): (1) Use activities that require student engagement with higher mental processes; (2) The instructor explains concepts, through prompting and providing challenging contradictory information, instead of providing answers directly; (3) Design instruction to allow students to restructure their prior understanding based on what is taught in class; (4) Use instruments or
38 techniques such as interviews, prediction-observation-explanation, drawings etc., to determine students’ prior knowledge; (5) Teachers could emphasize the relationship between the symbolic, macroscopic and microscopic worlds of chemistry and encourage students to develop their own mental models of chemistry concepts; (6) Teachers may foster conceptual understanding of abstract concepts through co-construction and mental evolution and; (7) Use activities, such as interviews, to allow students to generate, evaluate and modify their mental models on the particular scientific phenomenon (Barke, Hazari & Yitbarek, 2009).
The Role of Computer Simulations in addressing Student Misconceptions
Educators have devoted considerable time and effort towards developing digital technologies, such as computer simulations, to help students visualize concepts at the molecular level. Computer simulations are particularly helpful tools for chemistry since students can interact with the system, modify it and receive feedback about their predictions (Steiff & Wilensky, 2002).
Computer simulations that provide multiple representations such as the TEMBS simulation, can enhance student understanding by presenting the interactive and dynamic nature of phenomena and reducing cognitive overload by making schematics clear for students to interpret (Khan, 2007). In general, computer simulations with multiple representations, such as graphs, prediction questions, molecular representations and analogies, encourage students to generate, evaluate and modify their mental models on a scientific phenomenon. Computer simulations such as ChemLogo (Steiff
&Wilensksy, 2003), E-Chem (Wu et al., 2001), NetLogo (Steiff & Wilensky, 2003) and Thinking
Tags (Colella, 2000) were reviewed.
39 In terms of student outcomes, E-Chem has been shown to help students (1) to understand microscopic and symbolic representations to describe a process (2) to visualize the interactions among molecules (3) to understand how to explain concepts and (4) to understand molecules and atoms better (Wu, Krajcik & Soloway, 2001). NetLogo or connected chemistry (1) provides greater understanding of chemistry concepts by providing tools for students to engage and interact in an assimilated environment (2) allows students to practice problem-solving technique to gain greater understanding (3) identifies what difficulties students have when approaching complex topics through the teacher-student interaction or related worksheets (4) discourages rote memorization and encourages understanding and critical thinking while problem solving and (5) helps identify common misconceptions and help to clarify them with multiple representations for example graphing (Steiff & Wilensky, 2003). Thinking Tags (1) engage students in problem solving activity (2) develops inquiry skills from students’ personal experience and science understanding, and (3) allows self-regulated inquiry based learning in a collaborative environment (Colella, 2000).
The next paragraphs details each of the studies.
Wu, Krajcik and Soloway (2001) investigated how students used E-Chem (Figure 1) to build molecular models and view multiple representations in chemistry. The multiple representations consisted of videos of experiments, graphs and animations that students can view on three separate screens. These representations were intended to show macroscopic (observable changes), microscopic (motion of molecules, atoms, or subatomic particles) and symbolic
(symbols, numbers, formulae, equations, and structures) in chemistry. The study involved 71 grade
11 students at a small public high school. The research showed that both, 2-D and 3-D models should be provided through instruction. Students chose the space filling (3-D) model as a better
40 representation of a molecule and the 2-D model as a better representation of how many bonds there are.
Figure 1: Screenshot of E-Chem
Although students can make observations at the macroscopic level, their understanding of the concept is not clear because they are not able to see the structures or the motion of the molecules or atoms. Wu, Krajcik and Soloway (2001) suggested combining concrete models and technologies that afford viewing dynamic and three-dimensional animations to help students learn to use microscopic and symbolic representations to describe a process. Multiple linked representations allow students to visualize the interactions among molecules, understand how to explain concepts and promote greater understanding of molecules and atoms (Wu, Krajcik & Soloway, 2001). The limitation to E-Chem is that it appears that students cannot change or manipulate the data and obtain deeper understanding of how and what’s involved in the reaction.
Colella (2000) investigated Participatory Simulations called ‘Thinking Tags’ and how these can lead to new scientific understanding. Thinking Tags create a scenario where students are transformed into “players”. Thinking tags are small wearable computers that take the simulation off the computer and are attached physically to students. The students become “agents” in the
41 simulation. According to Colella (2000) these activities allow students to “dive into” a learning environment that engages them in a problem solving activity through inquiry and experimentation.
Participatory simulations create a scenario with a set of underlying rules that allows inquiry and experimentation. For example, the students were provided with a scenario where a virus is about to wipe out a small community. Students were asked if the inhabitants could discover a way to survive. As students waited, watching intently at a computer, the virus mysteriously infected a few players on the other side of the classroom. A set of red lights flashed indicating that a player had been infected. The players struggled to avoid being infected. Participatory Simulations take the simulation off the computer and bring it to the world of the student. The students are not watching the simulation but become the simulation. Questions such as “Who got them sick?
When? How? etc.” allowed students to discover their own viral epidemic. Thinking Tags allow self-regulated learning in the classroom where learning is inquiry based and there is collaboration between students (Colella, 2000).
Kozma’s research involved a software application called Multimedia and Mental Models in
Chemistry or 4M:Chem (Figure 2). The program was designed to allow students to interact with each other and socially construct an understanding of the concept. 4M:Chem software provided a way of exploring chemical systems using multiple, linked representations. The student starts by selecting an experiment, for example a chemical equilibrium system such as “N2O4 ⇔ 2NO2.” The system would be displayed as a chemical equation in the “control window”. The control window allows students to manipulate parameters such as temperature and pressure and see the effects of their actions as they view the simultaneous multiple, dynamic representations. The representations include a video of the reaction, dynamic graphs, displays of instrumental methods
42 used to follow the reaction, and the molecular-level animations of the reaction. For example the students could select the video window and change the temperature of the system in the control window. The video window would show the system as it appears on the laboratory bench, being heated and the changes in colour according to the shifts in equilibrium. The students may then select the graph window and rerun the reaction. A dynamic graph would show changes in partial pressures which increase or decrease as the system is heated and eventually reaches equilibrium. In the animation window, students view symbolic objects that represent the different species of molecules moving and colliding forming reactants and forming products.
43
Figure 2: Screenshot of 4M:CHEM
Kozma (1997) found significant differences between expert and novice chemists to understand chemistry using a variety of representational forms. They were given two multimedia cognitive tasks. The chemists were to view a number of computer displays in one of four representational forms: graphs, molecular-level animations, chemical equations, and video segments of experiments and carry out a number of activities. One of the activities was where they had to group the displays into meaningful sets. In other words, they had to match the right laboratory demonstration to the right molecular representation, graph or equations. The chemistry experts were able to do better and they were able to describe their clusters, e.g., “gas law” (Kozma, 1997).
44 In describing their observations, novices used surface features such as colour, while experts applied deeper conceptual understanding. The novices were not able to make connections between representations, even after interacting with the simulation. The understanding of novices was more dependent on surface features of particular representations and they could not connect chemical phenomena represented on one form to the same ones represented in another form. The surface features that novices identified did not explain enough about the underlying concepts. This study showed that students’ understanding is often restricted to the physical aspects of a scientific phenomenon and there is little about these surface features that relate to the underlying chemical processes. Secondly, it was found that students’ understanding seemed to be constrained by the surface features of symbolic systems and expressions used to represent science. For example, the surface feature used to represent equilibrium (⇔) did not convey to students its underlying dynamic nature. Many students had the misconception that at equilibrium, chemical reactions stop. According to Kozma (2000), the implication of this study was that science educators must find new symbol systems and symbolic expressions that would allow students to make connections between what they can see, manipulate and the underlying invisible science.
NetLogo is a multiagent modeling language employed in a variety of biology and physics classrooms. One of the applications of connected chemistry is NetLogo (Figure 3). In NetLogo students are able to control the behaviour of thousands of graphical agents. By exploring the relationship between the agents’ rules of behaviour and the patterns that emerge as a result of these rules, students are able to overcome many misconceptions that are generated as a result of their lack of understanding of micro and macro level interactions. According to Stieff and Wilensky (2003), connected chemistry provides tools for students to engage and interact in a simulated environment
45 to develop a greater understanding of chemistry concepts and processes (Stieff & Wilensky, 2003).
Connected Chemistry uses a “glass box” approach (Wilensky, 1999) that allows students to visualize the molecules and provides them with the opportunity to manipulate the representations.
For example, students can manipulate the code that makes the program run. Connected chemistry seeks to go beyond than just identifying and clarifying misconceptions.
Figure 3: Screenshot of NetLogo
NetLogo software helps to identify what difficulties students have when approaching complex topics such as chemical equilibrium (Stieff & Wilensky, 2003). The program consists of a plotting window, a graphics window and system parameters. The system parameters consist of sliders and buttons that students can play with and observe changes in the plotting and graphics window. The graphics window shows atoms and molecules represented with different colors and
46 students can see which molecules are increasing and which ones are decreasing. For example, when a student changes the temperature on the parameter window of the chemical equilibrium model, each molecule responds to the temperature change. With an increase in temperature, the frequency of collisions increases due to the increase in speed of the molecules. Therefore students can observe how changes in macroscopic properties, which they can make, affect the interaction of molecules at the microscopic level (Steiff & Wilensky, 2003).
According to Steiff and Wilensky (2003), chemistry teachers should use multiple representations, such as those found in connected chemistry to illustrate processes taking place at the microscopic level. A three-part 90 minutes interview was administered to six undergraduate science majors regarding the concept of chemical equilibrium. According to the study, students were found to employ problem-solving techniques characterized by stronger conceptual understanding and logical reasoning. In connected chemistry, students can change factors or variables of the chemical reaction they are looking at and make predictions based on their understanding of the chemistry concepts. They can then check to see if their predictions were correct and find ways to justify the correct responses. Students can therefore monitor their own learning through manipulation of the variables (Steiff & Wilensky, 2003). With NetLogo, the authors argued that students could visualize and explore how macro-level theories emerge from molecular interactions at the microscopic level (Steiff & Wilensky, 2003).
The TEMBS simulation (Sprague, Trey, Pillay, & Khan, 2005) includes all the features mentioned above such as: (1) Molecular view (2) Graphical view (3) System parameters that can be manipulated (4) Chemical equations and (5) Chemical structure descriptions. TEMBS simulation
47 also has a dynamic analogy view and a prediction feature that none of the above simulations feature.
The user interface of the TEMBS simulation Version 1 (Khan, 2008) includes several modules: a formula view, a slider view, a graph view, a description view, a prediction mechanism, a molecular view and a dynamic analogy view. Figures 4 and 5 illustrate each of these views. The formula view shows one of the four chemical reactions that have been currently programmed into the TEMBS simulation. Students can choose any one of four reactions. The slider view allows the student to modify conditions such as temperature, concentration, and volume in the closed chemical system. A graph view plots change in concentration of reactants and products over time.
The description view provides background information on the reactants and products involved.
The description view can be switched to a prediction view. During the prediction view the simulation is paused and then a multiple choice question will appear prompting students to predict the effects of changes before the simulation continues. The molecular view shows a magnified representation of the molecules interacting in the system. Finally the molecular view can be switched to a dynamic analogy view. The analogy view, in the Le Chatelier simulation, is a scale with reactants and products on either side attempting to reach equilibrium (Khan, 2008).
48
Figure 4: The TEMBS Simulation (Version 1) with formula view, slider view, graph view, molecular view and description view.
The disadvantage of using computer simulations in the classroom is that students can get carried away with clicking without thinking (Khan, Sprague, Trey, Pillay, & Disney, 2005).
Students are fascinated by the animations on the screen and may not take advantage of the learning that can take place, without guidance and structure. The teacher’s role as a facilitator may be necessary here.
The TEMBS simulation can support GEM cycle conceptual learning, and the following three features of the simulation achieve this: (1) A prediction mechanism that asks students to
49 predict the effects of a stress on the equilibrium based on their current models. Students’ predictions help them to evaluate (E) their prior models and make necessary modifications as a result of a conflict with data. (2) The analogy feature supports the generation of models. (G) model phase of the GEM cycle approach by helping students make a connection between the observable and unobservable phenomena. (3) Multiple views or representations of a chemical reaction helps students develop links between different chemistry symbol systems.
A Dynamic Analogy View of TEMBS Simulation
Analogies are commonly considered as a comparison between two different domains as a means for students to understand the unfamiliar by constructing similarities between what is already known and what is unknown (Duit, 1991; Khan & Chan, 2010). For example, a weigh scale is commonly used to represent a chemical equilibrium. Analogies are powerful for students’ cognitive development because analogies can help the learner build on and modify their prior knowledge (Gentner & Gentner, 1983). Shapiro (1985) suggested that analogies make mental processing more efficient by modifying existing cognitive structures prior to processing the new information, preparing existing structures in memory for new information.
Analogies may be presented in the form of a text, pictures, videos and verbal examples but to further enhance students’ visual perception of a phenomenon, some of the unobservable relationships addressed by the phenomena can be presented via computer simulation (Khan &
Chan, 2010). Teachers commonly use the weigh scale as an analogy to explain chemical equilibrium. Volland (1998) has shown how chemical equilibrium can be viewed like a balance
50 beam or a weigh scale with the reactants on the right hand side and the products on the left hand side of the balance beam. When the forward and reverse rates of the chemical reaction are equal the system is seen as “balanced”. The analogy view in TEMBS simulation depicts a scale with reactants and products serving as an analogy for a chemical reaction attempting to reach equilibrium in a closed system (figure 5).
Figure 5: The TEMBS Simulation with formula view, slider view, graph view, and analogy view.
The dynamic computer analogy in TEMBS is runnable via simulation when the student selects the analogy view. Some of the findings in the study by Khan and Chan (2010) of two Grade
12 chemistry classes that interacted with the TEMBS simulation were: (1) Overall conceptual gains
51 following interaction with the simulation (improvement in post-test scores) (2) Improvement in understanding reaction rates, specifically forward rates of reaction (3) Improvement in the “before” and “after” drawings of chemical equilibriums (4) compartmentalization view reduced from 46% in the pre-test drawings to 30% in the post-test (5) Students understood that the dynamic scale was an analog to chemical equilibrium (6) Dynamic analogy helped students visualize the dynamic nature of equilibrium (7) Students rated the dynamic analogy as helpful in comparison to other views. According to this study, interactions with the dynamic analogy and molecular views in the simulation helped students visualize molecules in motion. Their findings suggested that the
TEMBS simulation and the dynamic analogy were helpful in addressing several misconceptions that students hold in chemistry such as: (1) Compartmentalization view (2) When a stress is applied to a system at equilibrium, the rate of the reverse reaction will decrease as a consequence of the forward reaction rate increasing. Le Chatelier's Principle is an abstract and difficult concept for
Chemistry 12 students to understand because they can only make observations at the macroscopic level and not at the microscopic level.
In summary, all the different types of computer simulations mentioned in the readings have multiple representations. Students unable to conceptually link or make a connection between the three levels (symbolic, macro and molecular forms of representation in chemistry) may find it useful to engage with computer simulations that have such representations on a single screen.
Using computer simulations can potentially support students as they generate, evaluate, modify their molecular models of equilibrium. Computer simulations can promote students’ abilities to understand abstract, unobservable phenomena in chemistry by integrating multiple representations of the same phenomena (Khan, 2008).
52 Sequence of Instruction and Learning Cycle
Researchers found that using computer simulations may afford opportunities to promote students’ understanding of unobservable phenomena in science, however more recent studies have shown that computer simulations can be more effective if students are provided some guidance
(Kozma, 2000). A learning cycle approach is considered to be inquiry-based learning that promotes learning by guiding students through particular steps (Turkmen, 2006). In contrast, a traditional approach to instruction in science, such as those involving lecture, notes, and labs, tends to lead to shallow understanding because of its emphasis on memorization and recitation of facts
(Ozmen, 2002). A learning cycle teaching approach can address student misconceptions, improve problem solving, foster better laboratory skills, and also technological tools help to eliminate misconceptions (Turkmen & Usta, 2007).
One example of a learning cycle consists of three phases, “exploration,” “term introduction,” and “concept application” (Turkmen, 2006). In the exploration phase, for example, students of science gather and record data. This is information received from the outside world.
Students retain information that makes sense and reject what does not make sense. The exploration phase involves students interacting with a laboratory environment while collecting data formally or informally (Turkmen, 2006). The laboratory experience is more directed than pure discovery approach however care can be taken in ensuring that expected data is not revealed to students
(Turkmen & Usta, 2007).
Term introduction phase is when students are expected to address new ideas. The teacher can facilitate an interactive discussion with students where students redefine, change or invent mental structures. Students are considered to be in their accommodation phase as they make their
53 own meaning out of the observations. According to Turkmen and Usta (2007), students either construct a new mental structure to fit their experience or they may not construct a new mental structure and reject the experience.
In the concept application stage, students continue to make sense of the concept through more activities using additional resources such as technological tools. According to Turkmen and
Usta (2007), this phase aids in organizing and generalizing information by adjusting related mental structures and relating one context to another. According to Turkmen and Usta (2007), teachers should use a multidisciplinary approach that integrates technology, such as a computer or video, with other teaching strategies in the exploration and concept application phase.
Khan (2010) carried out a case study where she examined how an experienced science teacher taught chemistry using computer simulations and the impact of his teaching on his introductory chemistry students in a large North American public university. The study involved classroom observations over three semesters, teacher interviews and student surveys. Patterns in teacher-student-computer interactions and the outcome of these interactions on students’ learning were analyzed. The teacher involved in the study followed a pattern of “generate-evaluate- modify” (GEM) as a learning cycle to teach chemistry and the simulation technology was integrated in every stage of GEM. Thirty-three first-year chemistry, biochemistry, engineering, nursing, and education major with 11 students in an honours program in these majors participated in this study. Computer simulations that were integrated into this class did not replace the laboratories but represented the results of simulated lab experiments or the behavior of atoms of molecules under conditions not observable with the eye. Students were organized in pairs or groups of three at each terminal equipped with the Chemland suite of simulations.
54 GEM was illustrated with evaluation and modification instructional phases repeating themselves on an average, in one period of class, where the teacher engaged in this approach two times, for a total of 52 times across 11 different topics in chemistry. For example in the generation phase of this learning cycle the teacher demonstrated how to read large data sets and constrained initial variables that students utilized in the simulation. The teacher also selected the general scope of variables for students to investigate and encouraged students to generate a large amount of information on the variables in order to generate a relationship between them. The teacher then encouraged students to make graphs or view sets of models and encouraged students to dynamically generate graphs and multiple representations as output in the simulation. Still in the generation phase, the teacher asked students to predict, and on the simulation the teacher asked students to select extreme variables to view the effects. For example in the evaluation phase, the teacher asked students, “What’s wrong with this?”, “Why doesn’t this make sense?”. On the simulation, the teacher asked the students to rerun the graphs, select different variables, view the animations at the molecular level and make a prediction before utilizing the simulation. In the modification phase of the cycle, the teacher asked students to revisit their original relationships that were integral to their models. On the simulation, the teacher asked students to keep graphs and animations on the screen in order to evaluate relationships with their original one. The teacher was observed to be consistently directing students to the computer simulation technology during
GEM cycles. Analysis of the classroom observations, transcribed teacher interviews and results from student surveys revealed three main findings: (1) Technology integrated with GEM cycle is a three step coordinated pedagogical approach that involves generating, evaluating, and modifying student ideas (2) Simulation technology appears to afford teachers and students with the capacity
55 to critically analyze a problem, make unobservable processes more explicit and contribute to science learning in ways that go beyond textbooks (3) The teacher’s knowledge of specific teaching roles to help students identify subject area relationships using computer simulations and when and where to use simulation technology. Simulation technology integrated in every stage of GEM enhanced conceptual understanding of chemistry.
According to Khan (2010), the simulation technology integrated in every stage of GEM is an effective and viable pedagogy for teaching science with technology. The teacher, in this research, believed that the best time to introduce GEM with technology (T-GEM) is before concepts are introduced. Only after T-GEM were students instructed to use the textbooks to elaborate on what they learned. In the Khan (2010) study, the teacher followed the GEM approach as a learning cycle to teach chemistry and the simulation technology was integrated in every stage of GEM. There was a continuous discussion between the teacher and the students in every phase of the GEM cycle and during the students’ interaction with the simulation. In my research, when students are interacting with the simulation they only have a simulation activity sheet that provides instructions and asks prediction questions. There is no interaction between the teacher and the student. The teacher-student interactions take place during the lecture and discussion in the traditional phase of instruction. A learning cycle approach promotes inquiry- based learning and in my research the learning cycle approach is GEM. The TEMBS simulation encourages students to address any misconceptions they may have as they manipulate the parameters and generate, evaluate and modify their hypothesis.
56 Implications for Research
Despite a body of literature on how computer simulations can be used in chemistry
(Khan & Chan, 2010; Khan, 2007; Kozma, 2000; Steiff & Wilensky, 2003) to enhance students’ understanding of abstract concepts and to eliminate misconceptions in chemistry, little research has been done on how to teach with this technology. Khan (2010) in her study on “New Pedagogies on Teaching Science with Computer Simulations” has revealed that simulation technology integrated in every stage of GEM enhanced conceptual understanding of chemistry. The teacher in Khan’s (2010) study integrated the computer simulation in the curriculum such that the students learned concepts in an exploratory nature while the teacher used the GEM cycle approach to guide the students. In this study, the integration of a computer simulation with a GEM learning cycle approach based on model-based learning is being researched. The research aims to identify when would computer simulations be most effective if introduced into the chemistry classroom instruction. Would there be any difference if computer simulations are introduced to students before traditional forms of instruction, such as lectures and labs, or after?
Further research needs to be done on how to incorporate computer simulations in the classroom. Research has shown that traditional forms of instruction alone may encourage student misconceptions (Teichart & Stacy, 2002). Student misconceptions may also be attributed to inappropriate teaching methods, language in textbooks and students’ prior knowledge (Barke, Hazari & Yitbarek, 2009). Some teaching strategies that have been suggested are: (1) Use activities that require student engagement with higher mental processes
57 (2) Use instruments and techniques, such as interviews, to allow students to generate, evaluate and modify their mental models and (3) Use digital technologies such as computer simulations to help students visualize concepts at the molecular level.
Computer simulations with multiple representations encourage students to generate, evaluate and modify their mental models on a scientific phenomenon. While studies on computer simulations such as ChemLogo (Steiff & Wilensky, 2003), E-Chem (Wu et al.,
2001), NetLogo (Steiff & Wilensky, 2003) and Thinking Tags (Colella, 2000) were reported, there has not been much research on the implementation of a computer simulation in the classroom instruction. Therefore further studies are required to determine when computer simulations could be integrated with other forms of instruction such as lecture, notes, labs, etc.
Summary
In this chapter I provided the theoretical framework, model-based learning, for this study. Model based learning is a dynamic learning cycle that leads to a change in one’s mental models while inquiring about phenomena (Khan, 2007). I reviewed literature on: (1)
Possible sources of student misconceptions in chemistry; (2) Misconceptions in chemical equilibrium; (3) Teaching strategies to address student conceptions; (4) The role of computer simulations in addressing student misconceptions; (5) A dynamic analogy view of TEMBS simulation and; (6) Sequence of instruction and learning cycle. I also made implications for further research.
58 CHAPTER THREE
METHODOLOGY
My research questions for this study are: (1) How can computer simulations that have multiple representations e.g., TEMBS simulations, contribute to student understanding of difficult chemistry concepts, such as Le Chatelier’s Principle? (2) What is the most effective sequence of instruction for improving student achievement in Chemistry 12? Is there a difference in students’ achievement between: a) traditional instruction (lecture and labs) preceding computer simulation or b) computer simulation preceding traditional instruction?
PRELIMINARY RESEARCH
As part of a pilot study I carried out in my Chemistry 12 course, the students used a computer simulation on chemical equilibrium and the application of Le Chatelier’s principle. The research question for the Pilot Study was: Would students working on a computer alone or in pairs improve students’ performance on assessments? The instruments used in the Pilot Study included
Le Chatelier’s Principle Pre-test and Post-test.
The research contexts were two Chemistry 12 classes. Fifty-two students from different ethnic backgrounds participated in this study. Most of these students were future candidates for post secondary institutions with the majority going into universities. These were high achieving and motivated students. The simulation used in this study was designed by Blauch (1998) (Figure
6). The simulation had three variables that could be manipulated and the changes in the concentration of reactants and products could be seen only as an increase or decrease instantaneously. While the simulation was quite effective in showing how the concentrations
59 changed when pressure or temperature was changed, it failed to show how the concentrations would change with respect to forward and reverse reactions over time.
Figure 6: Screenshot of Davidson Simulation
The Pilot Study research investigated whether the Davidson simulation on Le Chatelier’s principle was more effective in improving student understanding of chemical equilibriums if students worked individually or if they worked in pairs on the simulation. The research involved both classes receiving instruction in the same order (Table 2). At the end of the traditional form of instruction, students in both classes were given a pre-test (Appendix J i). Both classes then worked on a computer simulation on Le Chatelier’s Principle (Davidson Simulation, Figure 6) where one class worked individually on the simulation and the other class worked in pairs on an
60 activity sheet on the simulation (Appendix K i). The students in both the classes were then given a post-test (Appendix J ii).
Table 2: Pilot Study Research Plan for the Two Chemistry 12 Classes Class A Class B
Traditional form of instruction, i.e., lecture, Traditional form of instruction. demonstrations, lab, etc. Pilot Pre-test (Individually) Pilot Pre-test (Individually) Davidson Computer Simulation Activity (Pairs) Davidson Computer Simulation Activity (Individually) Pilot Post-test (Individually) Pilot Post-test (Individually) Pilot Study Student Survey Pilot Study Student Survey
Data Source 1. Pilot Pre-test. At the end of the traditional form of instruction students were given a pre-test, which consisted of multiple choice questions and open-ended questions
(Appendix J i).
Data Source 2. Pilot Post-test. At the end of the simulation activity students were given a post- test similar to the pre-test (Appendix J ii). Both tests had similar questions that tested conceptual understanding. For example one of the questions were as follows:
10. Consider the following equilibrium:
2 NO(g) + Cl2 (g) ⇔ 2 NOCl(g) ΔH= -77 kJ
What happens to the amount of Cl2 when the following changes are imposed? Explain, using
Le Chatelier’s principle. a) Removing NO(g). (1 mark) b) Decreasing the temperature. (1 mark)
61 Data Source 3. Pilot Study Student Survey. After the post-test students were given an open-ended survey (four questions, Appendix K). The generally addressed: (1) What they found to be most difficult to understand in the chemical equilibrium unit and (2) What did they learn from the Davidson simulation?
In the pilot study, the pre-test scores were not significantly different. The post-test results, however, indicated that students working in pairs did significantly better on the post-test when compared to the students working individually (n= 40). Class A showed a significant (p = 0.0256) improvement in test scores, increasing from an average of 43.8% on the pre-test to 63.2% on the post-test. Class B’s average changed from 51.3% in the pre-test to 58% in the post-test, a change that was not statistically significant. The difference in instruction between the two classes was that class A collaborated in pairs and class B worked individually. This may be the reason why class A did significantly better than class B. The extra discussion that students were having during the simulation may have contributed towards a better understanding of the concepts.
My pilot research affirmed that computer simulations, such as the Davidson simulation, could be used to enhance conceptual understanding of abstract concepts with the evidence of higher test scores; I now wished to further investigate the best time to introduce computer simulations in an instructional sequence. In the main research, the students did not work in pairs but worked individually on the simulation. However they worked in groups of three to four students while working on the Equilibrium Project.
62 RESEARCH DESIGN
The research design adopted was quasi-experimental since students were not randomly selected and entire classes, not individual students, were assigned to two treatments. Furthermore, the study followed a non-equivalent control group design. One class (Class A) received instruction in the traditional form and then interacted with the simulation, while the other class (Class B) interacted with the simulation first and then received instruction in the traditional form. The students were kept in existing classrooms intact. Each class was randomly subjected to the treatments.
CLASSROOM CONTEXT
The research for this study was conducted in a classroom, and students used laptops. The school is well equipped with computers. There are three computer laboratories in the school. Each laboratory has 35 computers. There are also two sets of well maintained mobile labs that contain
30 laptops each. The students used one set of mobile labs and worked on the simulation individually.
PARTICIPANTS
Participants were students from two Chemistry 12 classes in a suburban school with a population of about 1400. There were a total of 46 students (24 females and 22 males). This public school is located in the central area of Surrey, Canada. A multi-cultural group of students from a range of socio-economic backgrounds make up the student population. Most of the students taking Chemistry 12 planned on pursuing a career in chemistry or taking further studies at
63 post-secondary level. Although each student successfully completed Chemistry 11, the concept of equilibrium had not been introduced in previous grades. Students are introduced to the concept of chemical equilibrium for the first time in Chemistry 12. The first unit, Reaction Kinetics, only addresses reactions that go to completion and do not reach equilibrium. Therefore students have no prior knowledge of reactions that reach equilibrium until they are introduced in unit 2, Chemical
Equilibrium, of the Chemistry 12 curriculum. This study took place during the Chemical
Equilibrium unit and students had no prior knowledge of Le Chatelier’s principle and Chemical
Equilibrium. These students did not have any experience with computer simulations in the
Chemistry 12 classes prior to the research. The students have a range of ethnic backgrounds, academic abilities and socioeconomic levels with the majority from middle-class families. The study took place over a period of two weeks.
I was the only teacher teaching Chemistry 12 at the school in the semester during which this study took place. Students were invited to participate in this activity by a colleague who also teaches Chemistry 12 but not during this semester (Please see 'Student Invitation Letter’
(Appendix C i) and 'Student Consent Forms’ (Appendix Cii). Consent for the survey (Appendix
H i) was obtained along with the student consent forms prior to the survey. All activities and instruction during this study were part of the normal instruction in the Chemistry 12 curriculum.
The TEMBS simulation was a new activity but it was directly related to chemical equilibrium and the application of Le Chatelier's principle, and this content is part of the Chemistry 12 curriculum.
All participants were granted two weeks to decide whether or not they wished to participate in the research. Students who did not consent still participated in all the activities as this was normal
64 instruction, but they were excluded from the data set. In addition, there were some students who were taking the course for the second time.
Since this study took place in the fall, it is likely that students who were enrolled in the course in the summer and did not receive the grades they needed, would most likely take Chemistry again. This study assumed that the students had partial or limited prior knowledge on chemical equilibrium, therefore the students taking the course for the second time were included, but their scores were not considered for research purposes. The post- test scores of all the students were recorded towards their grade in the course, including the students taking the class again. Students who did not have their scores considered for research purposes had their scores removed by the colleague.
RESEARCH METHODS AND PROCEDURES
The following instructional sequence and data gathering was carried out with two classes of
Chemistry 12 students (Table 3). Descriptions of the instructional sequence and instruments follow the table. The lesson objectives were as follows: (1) Describe the dynamic nature of chemical equilibrium (2) Describe chemical equilibrium as a closed system at constant temperature
(3) Describe the term ‘shift’ as it applies to equilibria (4) Apply Le Chatelier’s principle to the shifting of equilibrium involving changes in temperature, concentration and volume of gaseous substances (5) Explain the shifts using the concepts of reaction kinetics (6) Identify the effect of a catalyst on dynamic equilibrium (7) Apply the concept of equilibrium to a commercial or industrial process.
65 Table 3: Thesis Research Plan with Two Classes of Chemistry 12 Students.
Class A and Class B Equilibrium Primer Equilibrium Pretest Introduce group Equilibrium Project
Class A Class B Traditional TEMBS Simulation (Lecture, Labs, Demos, etc) Equilibrium Interview 1 Equilibrium Interview 1 Equilibrium Mid-Test Equilibrium Mid-Test Equilibrium Survey 1 Equilibrium Survey 1
Class A Class B TEMBS Simulation Traditional
Equilibrium Interview 2 Equilibrium Interview 2 Equilibrium Post-Test Equilibrium Post-Test Equilibrium Survey 2 Equilibrium Survey 2 Presentation of Equilibrium Project Presentation of Equilibrium Project
This research design addresses the two research questions in the following ways: (1) Phase
1 involved both classes receiving an introduction to the unit (referred to as the primer in this study) and at the end of the primer, students wrote a Pre-Test (Appendix F i) that indicated the distribution of students in terms of ability, as measured by this Pre-Test. The tests were not graded until after the course was over. The students were also assigned the Equilibrium Project that was due at the end of the entire sequence of instruction (2) During Phase 2 Class A received instruction according to traditional methods (Lecture, Labs, demonstrations, and exercises) and
Class B worked on the simulation. Each student worked on the simulation individually. The students were provided with a simulation activity sheet (Appendix I i). This consisted of
66 instructions students needed to follow while working on the simulation as well as questions related to the instructions. The following is a sample item:
1. For the following reaction:
PCl5 ⇔ PCl3 + Cl2
a) Draw this system at equilibrium using molecules and explain your drawing (Use different colors to represent the molecules and include a legend). Draw the molecules at time t1 and t2 to illustrate the equilibrium. t1
t2
b) i) Predict what would happen to the concentration of Cl2 and PCl3 if the concentration of PCl5 were increased? Draw the system to show changes in the equilibrium that would take place in the following situations:
Initially (When PCl5 is added)
Changes in the concentration of Cl2, PCl3, and PCl5. c) Generate a “rule” regarding concentration and its effect on a chemical reaction at equilibrium. d) Now go to the simulation on your computer. Run the simulation for 30 seconds approximately and evaluate the relationship you constructed in c). You can increase the concentration of PCl5 by moving the PCl5 slider. Click on ‘Start’ under the molecular screen. Look at the graphs and the molecular view and modify your initial rule if necessary below. Explain what you have changed and why.
The simulation activity sheet had instructions for students to follow, diagrams to draw and prediction questions to answer as they interacted with the simulation. There were no discussions between the teacher and the students. The teacher only provided assistance to some students who were having difficulty connecting to the simulation and helped to simplify any instructions when necessary. At the end of this phase both classes wrote the same Mid-test (Appendix F ii). The students were also interviewed for the first time. The interview questions attempted to determine
67 students’ understanding of chemical equilibrium (Appendix G ii). (3) Phase 3 involved a switch, where Class A worked on the simulation and Class B received instruction according to the same traditional methods above. At the end of phase 3, both classes wrote the same Post-Test
(Appendix F iii). The students were also interviewed on their Equilibrium Project. All the students completed a survey at the end of phases 2 and 3 (Appendix H i and Appendix H ii). The surveys indicated how students felt about chemistry, in what ways did they learn chemistry, and methods or procedures they found to be most effective. Therefore the only difference in the form of instruction between Class A and B was the placement of simulations in the sequence of instruction.
DATA SOURCES
Two sets of data were collected. Quantitative data collected were pre-test, mid-test, post- test and student surveys (Part 1). Qualitative data collected were student surveys (Part 2) and student interviews of the equilibrium project. The data sources in total were: (1) Equilibrium
Project Student interviews (2) Tests and (3) Surveys.
Equilibrium Project Student Interviews. All students were also assigned a project at the start of the unit. The project involved students drawing a representation of their understanding of
Chemical Equilibrium and the application of Le Chatelier's Principle. The interviews conducted in relation to the project were collected as qualitative data. The students were given class time to work on their projects and also time during their tutorials after school. Students presented their final representations to the class at the completion of the unit. This project was a normal part of their instruction in Chemistry 12. Students used analogies such as different coloured dots, ballroom
68 dancing, house parties, etc., to represent reactants and products. Students did not receive specific instructions on what kind of presentation to make. The students spontaneously generated their own models, which they reviewed continuously with each other and the teacher during the interviews.
The purpose of the interview was to allow the teacher to identify possible misconceptions and difficulties in understanding the concept of chemical equilibrium, generated as they worked on their projects. The student modified their responses to the questions in the interview process as they approached the end of the project. There were seven groups of students in each class. The groups were interviewed separately, one group at a time. The rest of the students remained in the classroom and worked on their projects. Interview Consent was also obtained (Appendix G i).
Those students who had not consented had their voices erased when the data were analyzed after the course was over. The interview questions were more specific, as outlined on the question sheet, but the later interviews involved questions generated as a result of what students had drawn and the questions became more evaluative as the interview continued (see Appendix G ii, 'Interview
Questions'). The interviews were about 10-15 minutes long depending on student responses. The questions attempted to allow students to generate, evaluate and modify their own models. For example, “How would you show that the reaction has reached equilibrium?” The interviews that took place during these stages were audio taped. Students who did not consent to audiotaping were not audio taped. Had a non-participant voice been inadvertently captured on audiotape, the information was not used in any data analysis or presentation. The audiotaping took place during normal classroom lessons. All the audio recordings, from the two sets of interviews, were transcribed.
69 Equilibrium Pre-tests, Mid-tests and Post-tests. The tests consisted of 5-10 multiple- choice questions and a set of 3-5 open-ended questions. The questions were designed to assess students’ understanding of the concept of chemical equilibrium at the end of each phase of instruction. The pre-test identified the distribution of students in terms of ability. It also served as a standard in order to compare the other tests with. Its comparison with the mid-test for both the classes indicated which method of instruction had a greater effect on improving student understanding. The pre-test was given after the primer. The primer was based on lessons that addressed the following learning outcomes:
• Look at potential energy diagrams
• Determine entropy and enthalpy changes from a chemical equation (qualitatively).
• State that a system will tend toward a position of minimum enthalpy and maximum
entropy
• Predict the results when enthalpy and entropy factors favour products, favour reactants or
oppose each other.
The mid-test compared as to which method of instruction was more effective in terms of improving student performance by comparing the results to the pre-tests. The post-test compared which sequence of instruction was the most effective shown by comparing the post-test score between the two classes.
Equilibrium Surveys. Students completed Equilibrium Survey 1 at the end of the first stage of interviews (Appendix H i). At the end of the entire sequence of instruction students completed a second survey. The surveys were taken verbatim from a previously published work called “Model-Based Inquiries in Chemistry” (Khan, 2007).
70
Data sources were as follows:
Data Source 1. Equilibrium Pre-test. The pre-test consisted of multiple choice and open ended questions (Appendix Fi) designed to assess students knowledge on the introductory material as mentioned earlier. The questions were made by the teacher and reviewed by another chemistry teacher, as well as an expert in chemistry education. The following is an item from the pre-test:
Consider the following exothermic reaction:
C3H8(g) + 5O2(g) --> 3CO2(g) + 4H2O(g) + heat a) Will the above reaction reach equilibrium? Yes or No. (1 mark) b) Explain in terms of increasing or decreasing entropy and enthalpy. (2 marks)
Data Source 2. Equilibrium Mid –test. Students wrote a mid-test similar to the pre-test (see
Appendix F ii). The following is a sample question:
Consider the following equilibrium:
2NF2(g) ⇔ N2F4(g) a) Equilibrium shifts to the right when volume is decreased. Describe the changes in reaction rates that cause this shift to the right. (2 marks) b) i) Draw a diagram (graph) to represent what you may see at the molecular level initially when the volume is decreased. (2 marks)
ii) Draw a diagram (graph) describing what happens to the system, as equilibrium is re-established. (2 marks)
71 Data Source 3. Equilibrium Post-test. A post-test that was similar in format to the pre and mid test was given. A sample item is as follows:
8. Consider the following graph for the reaction: H2(g) + I2(g) ⇔ 2HI(g)
1.0 (0.8)HI 0.8 Concentration (0.6)H2 (mol/L) 0.6
0.4 (0.2)I2 0.2
0 t1 t2 t3 Time
The temperature is increased at t1 and equilibrium is re-established at t2. a) On the graph, sketch the line representing the [HI] between time t1 and t2. (1 mark)
b) Calculate Keq at time t2 – t3 (2 marks) c) Generate molecular level models (Use some form of representation such as dots, stars, etc) to show what is happening in the situation above from t1-t3. i)Your models must show how molecules of HI, H2, and I2 will change in concentration. (1 mark each) ii) Provide a possible explanation for each model below the diagram. (1 mark each).
i) At t1 ii) Time t1 – t2 iii) Time t2 – t3
Data Source 4. Equilibrium Survey 1. Students completed a likert-scale questionnaire
(Appendix Hi). The general aim was to identify students’ attitudes towards chemistry instruction
72 in the classroom, computer simulations and chemistry in general. The following are sample items from the survey:
1. Chemistry is one of the more interesting sciences.
2. There are more frequent opportunities to generate scientific ideas in this class than in most other classes.
3. Peer discussion is valuable for my understanding of science topics
Data Source 5. Equilibrium Survey 2. Students completed the second questionnaire (Appendix
Hii). The survey aimed to identify student views on computer simulations and computer programs in general:
1. Demonstrations of chemical phenomena are more effective for my learning than an interactive simulation to the same chemical phenomena.
2. I become frustrated if a computer program does not respond according to my expectations.
3. I believe educational computer programs can help me learn.
Data Source 6. Equilibrium Project Interviews.
DESCRIPTION OF THE INSTRUCTIONAL SEQUENCE
The learning cycle involved in the instructional sequence was a GEM approach based on model-based learning. The multiple representations, involving the molecular view, analogy view, graphical view, prediction questions and chemical equations in the TEMBS simulation allowed students to generate their mental models of chemical equilibrium. Students were
73 given instructions on a simulation activity sheet (Appendix Ii) with prediction questions.
Students were also asked to draw graphs and “before” and “after” diagrams of molecules and how the system would respond to changes in conditions such as temperature, pressure, etc., according to Le Chatelier’s Principle. This process encouraged students to generate their mental models indicating their understanding of Le Chatelier’s Principle. Students were then instructed on the activity sheet to manipulate the variables on the simulation and compare their answers, drawings or graphs to what was generated on the simulation. This process encouraged students to eliminate any misconceptions and modify their mental models on chemical equilibrium if necessary.
The mid-test and post-test had some questions that attempted to gauge students’ model-based learning. These items were similar to those presented to students in the simulation activity sheet (Appendix Ii), for example: c) Generate molecular level models (Use some form of representation such as dots, stars, etc) to show what is happening in the situation above from t1-t3. i)Your models must show how molecules of HI, H2, and I2 will change in concentration. (1 mark each) ii) Provide a possible explanation for each model below the diagram. (1 mark each).
i) At t1 ii) Time t1 – t2 iii) Time t2 – t3
Traditional Method. This included lecture, discussion, labs, and demonstrations. This is part of the normal process of instruction. Simulations were not considered part of this method.
TEMBS Simulation. The simulation was used over the same number of days as the traditional method. The teacher’s role during students’ interaction with the simulation was that of a
74 facilitator. Students followed instructions on the activity sheet and answered questions as they interacted with the simulation. At the end of both instructional approaches, the traditional class and the simulation class, students wrote the mid-test.
TEMBS STUDY DATA ANALYSIS
Quantitative Data
The quantitative data in this study are the Equilibrium pre-test, post-test, mid-test and surveys. The statistical test used in this study to analyze the tests was ANOVA
(analysis of variance). The software program, Merlin, was used to conduct the analysis. The
ANOVA test is a simple analysis of variance used to determine if there is a significant difference between means at a selected probability level. The means of the pre-test, mid-test and post-tests for the two classes were compared. An ANOVA test was performed instead of a t-test since the data are not normally distributed (Class A has 22 students whereas Class
B has 24 students). Therefore according to the ANOVA if p< 0.05 then the null hypothesis is rejected, and at least one of the sets is significantly different. The data below were evaluated with 95% confidence, which is the accepted confidence interval in data analysis.
For the surveys, students responded either strongly agree (SA), agree (A), neutral (N), disagree (D) or strongly disagree (SD). For each question the total number of student responses as either, SA, A, N, D, SD, was counted and then averaged out of the total number of students. The total percentages of students who strongly agree or generally agree or strongly disagree or generally disagree were calculated for each question. The percentages
75 were tabulated in terms of differences in responses between the class that received traditional first and the class that received the simulation first. The survey also asked students to rank in order from the most to the least effective form of instruction or learning. Out of a total of six different forms of instruction, the top three forms of instruction are reported based on student responses. The top three forms of instruction were nominated by the highest number of students. The total number of students choosing each type of instruction as the most effective form of instruction for them was counted.
Qualitative Data
The qualitative data involved interview data. For the interviews, all the recorded conversations with the students were transcribed. The interviews were coded for dialogue that suggest misconceptions in understanding the concept of chemical equilibrium as well as dialogue that are generated later showing a clarification of the misconception. The constant comparison method of analysis, which involves combining inductive behaviour coding with simultaneous comparison of all observed events (Glaser & Strauss, 1967; Strauss, 1987) was used. The method used here is grounded theory that aims at generating a theory that explains a concept. The theory generated by the interviews is regarding student mental models on the concept of chemical equilibrium. Since the interview took place in two phases, a comparison was made of student responses before and after a sequence of instruction. The interviews aimed to observe the changes in students’ conceptual understanding over the duration of the interviews. The interviews helped the teacher to identify students’ misconceptions.
The following is a transcript from the interview on the project students were working on:
76 S2- …and then in the second stage, the concentration is changing so there are some products and equilibrium is slowly being reached…and in the final stage equilibrium is established and the concentrations are now constant. T- How would you know that?
S2- We will show that the mole ratio is the same… T- Mole ratio is the same? What do you mean by that? Compared to what?
S2- Compared to what it was initially. S1- The same number of reactants and products… S3- I think we should also draw another stage exactly the same…like constant…to show there are no changes…so it’s constant…meaning equilibrium is reached…they will have the same number of molecules…so its staying constant. T- What is staying constant?
S3- The molecules…like three here and three here. T- What about the molecules is staying constant?
S3- The number of them so there is 3 here and 3 there. T- What do the numbers indicate? What quantity are we looking at?
S3- The forward and reverse rates should be equal. T- That’s one factor…what else tell us that the reaction has reached equilibrium?
S3- The concentrations are constant
In the interview segment above, the misconception student S2 has is that at equilibrium the mole ratio is the same, however this is a characteristic of all chemical reactions including those reactions that don’t reach equilibrium. Student S1 also expresses a misconception that at equilibrium the number of reactants and products is the same. However, at equilibrium the concentrations of reactants (number of molecules) and products stay constant but do not have to be equal. Student S3 makes this clarification as seen above.
RELIABILITY OF THE DATA
Reliability is the extent to which results are consistent over time (Joppe, 2000). In terms of reliability of the data, student and parent consent forms were assigned and collected by a colleague, who is also a chemistry teacher. This was done to ensure that students or parents who had not
77 consented were not known to the teacher. She also assigned student identification numbers randomly so that the teacher would not be able to identify work submitted by students. The same teacher reviewed the Pre-test, Mid-test and Post-test questions and the marking keys. For inter- rater reliability, two chemistry teachers evaluated the tests, one at the same school and the other from a neighbouring school. An inter-rater reliability of 0.96 was achieved. Both teachers met to evaluate sample responses to questions, and discuss and clarify the marking schemes for all the tests. To account for any discrepancies, questions that were not graded the same were discussed in an attempt to come to consensus. If there were any differences that remained after the discussion then the scores were averaged.
Validity of the Research
The inability to randomly assign individuals to treatments adds validity threats such as regression and interactions between selection, maturation, history, and testing. The more similar the intact groups are, the stronger the study. An advantage of this quasi control design is that since classes are selected as is, possible effects from reactive arrangements are minimized. History is not likely to be a factor contributing to validity threat in this research since the research only lasted less than ten school days. During this time there were no external factors that could interfere with the results. In terms of maturation, once again given the short time, there were no physical, emotional and intellectual changes in the participants. Testing may likely have been a threat since the time between the tests was short and there was also a mid-test in between. However, since the questions on the post-test were not based on factual information and students could not just answer by recalling, the nature of the questions reduces the chances of pre-test sensitization. The
78 test questions were peer reviewed by two chemistry teachers and questions that were not valid, based on disagreements, were removed from the tests. There was no validity threat in the form of regression since both classes were similar in terms of their performance ability. This was confirmed by the ANOVA test of the pre-test results indicating that the two classes were not significantly different. Selection of participants also did not add a validity threat since both classes were regular chemistry 12 classes.
ETHICAL CONSIDERATIONS
Protection of Privacy/Confidentiality/Anonymity
I wish to clarify the issue of potential coercion when teachers research their own practice.
The following points elucidate my approach: (1) The teaching approach and strategies used occurred as part of the way the unit is normally conducted rather than as a reason for the research
(2) In the Student Consent Form, students were assured that their participation was voluntary and that their participation would not influence the direction or manner in which they or their peers would be taught, nor how the class would be conducted. Students were assured that data collection and analysis of written course work would not occur until after the course was completed (3) I was the only teacher teaching this course and there were no other researchers present in the room; therefore the students' obligation to participate was not lessened.
The volunteer teacher met with my Chemistry students in class. The study was explained to students and students were invited to be in the study. Students were informed about the research nature of the class during the unit on chemical equilibrium through the consent forms
(Appendix C ii) and Student Invitation Letter (Appendix Ci). Students were further informed that
79 participation was entirely voluntary and their participation or lack thereof would not affect their grades in class. The parents of the participants were also informed about the research through a parent letter and a parent consent form. Students who wished to participate and obtained parental consent were included in the data collection; all other students took part in the unit of instruction, but were not part of the data set. Students also completed a Student Consent form.
Students participating in the study were assigned a code, a numerical identifier, by the volunteer teacher. The students used their codes for all tests and questionaires. All the tests were a normal part of the instructional sequence. The data were only analysed after the course was over and students were assigned their grades. Students who had not consented were excluded from the data set.
Consent/Assent
Consent from the Principal, the Surrey School Board, the Chemistry 12 students participating in the study and their parents were obtained through consent forms and letters. The students were not pressured in any way to participate in this study. They were informed that they would be involved only on a volunteer basis. It was made clear that parts of the audio cassette that captured students who did not consent to be in the study would be removed.
The students were given the consent forms (both parents and students) two weeks prior to the start of the study. The students were informed that this research was entirely voluntary and that they may refuse to participate or withdraw from the project at any time without jeopardizing their class standing, grades, or relationship with the school (please see 'Student Consent Form,
Appendix C ii). Students were also informed that they would be using numerical identifiers
80 assigned by the volunteer teacher. Informed consent from the Principal was obtained (Appendix
A).
To ensure that students participating in the course were not coerced in any way, a special informed consent process was used for this study. The students were informed that the study was directly related to their normal instruction on the unit of chemical equilibrium. The simulation would be new to instruction but it was designed to explain the concept of chemical equilibrium, a unit that is part of the Chemistry 12 curriculum. Participants were told that, as students, they would be expected to engage in all class activities, which were also the research activities. Due to the informed consent process, I had no idea who engaged in the activities solely to fulfill the requirements of the course and who engaged in the activities both as a student and as a research participant. The students' participation was voluntary, and whether or not they participated did not influence the direction or manner in which they were taught, nor how the class was conducted.
All data collection and analysis of written work did not occur until after the course was completed. Review and analysis of data only began after the course was completed and grades had been posted. Any course work that became data for this study was course work that was required for all students in the class. Students' participation in this research did not affect their grade in any way. To insure this they were asked to fill out consent forms, by the volunteer teacher who is also a chemistry teacher but was not teaching Chemistry 12 that semester. The volunteer teacher sealed consent forms in an envelope and placed them in a secure cabinet in the Science Prep room of the
School. The envelopes were not opened until after grades had been posted. This exact procedure was enacted on the last day of class, except the envelopes were clearly marked with the word
"Final" on the outside.
81 At the time when the grades were posted, I still had no idea whether any particular student had opted to participate in the research or not. I then unlocked the cabinet and looked at the second or "Final" consent form to determine who was participating in the research. This allowed the student the chance to change their minds after having engaged in all of the class/research experiences. Students were informed that their participation level would not affect them in any way and that they may withdraw from the study at any time.
Summary
In this chapter I have described the preliminary research and the methodology of this research. The methodology includes: (1) Research Design; (2) Classroom Context; (3) Participants
(4) Procedure; (5) Data Sources; (6) A description of the instructional sequence; (7) Data analysis;
(8) Reliability of the data and; (9) Ethical considerations. The data sources in total are pre-test, mid-test, post-test, surveys and interviews. In the next chapter I have listed all the findings in this research.
82 CHAPTER FOUR
RESULTS
As mentioned previously, my research questions are: (1) How can computer simulations that have multiple representations (e.g., TEMBS simulations) contribute to student understanding of difficult chemistry concepts, such as Le Chatelier’s Principle? (2) What is the most effective sequence of instruction for improving student achievement in Chemistry 12? Is there a difference in students achievement between: a) traditional instruction preceding computer simulation or b) computer simulation preceding traditional instruction? The first research question is partly addressed by the literature review. The initial interviews also either confirm or disconfirm the existence of misconceptions among the student population in this study. The final interviews after the students have interacted with the simulation confirm students’ understanding of the concept of chemical equilibrium. Statistical analysis comparing the pre, post and mid tests address the second research question regarding the most effective sequence of instruction.
Based on an analysis of the quantitative and qualitative data, three main findings emerged.
The findings are discussed including students’ conceptual understanding of the concept of chemical equilibrium through the pre and post-tests and their interviews based on the equilibrium project.
Finding 1. Both classes had similar achievement levels on the pre-test.
According to the ANOVA test analysis of the Equilibrium Pre-test results (overall test score /19), p = 0.92 (n=46). Since p > 0.05 there is no significant difference between the two classes in terms of their prior knowledge on the topic and their ability level (Table 4).
83 Table 4: Equilibrium Pre-test Analysis
Traditional First Simulation First Mean 10.93 10.83 Standard Deviation 2.56 3.55 95% Confidence 0.05 0.07 ANOVA 0.92
Finding 2. Traditional First or Simulation First achieve similar learning outcomes on the Equilibrium Mid-test.
According to the ANOVA test for the Equilibrium Mid-test results (overall test score /21) p = 0.12 (n=46). Since p > 0.05 there is no significant difference between the two classes indicating that traditional means of instruction on its own and simulation alone achieves similar learning outcomes (Table 5).
Table 5: Equilibrium Mid-Test Analysis
Traditional First Simulation First Mean 10.84 8.52 Standard Deviation 5.67 4.15 95% Confidence 0.11 0.09 ANOVA 0.12
Results therefore show that both groups of students’ achieved similar learning outcomes on the concept of chemical equilibrium.
Finding 3. Overall improvement in student understanding of chemical equilibrium detected following interaction with the simulation on the Equilibrium Post-test.
84 According to the ANOVA test analysis of the Equilibrium Post-test results (overall test score / 19), p = 0.04 (n=46). Since p <0.05 there is a significant difference between the two classes
(Table 6). The class that received traditional instruction first and then interacted with the simulation (Class A) performed significantly better than the class that interacted with the simulation first and then received traditional instruction.
Table 6: Equilibrium Post-Test Analysis
Traditional First Simulation First Mean 13.61 11.21 Standard Deviation 4.26 3.80 95% Confidence 0.07 0.07 ANOVA 0.04
Therefore since the p value is greater than 0.05 for the pre-test and the mid-test, the null hypothesis is accepted for the pre-test and mid-test indicating there was no difference between Class A and class B. However for the post-test, the null hypothesis is rejected since the p value is less than 0.05 indicating that in the post-test, the class that received traditional instruction and then used the TEMBS simulation performed significantly better than the class that interacted with the simulation first and then received traditional instruction.
85 Finding 4. Teacher discussions in class as top most effective learning experience according to Equilibrium Survey 1.
Table 7: Analysis of Equilibrium Survey 1
Statement Traditional First (%) Simulation First (%) Chemistry is one of the more interesting sciences 80 % agree 76 % disagree There are more frequent opportunities to generate scientific ideas 50% agree 76% agree in this class than in most other classes Peer discussion is valuable for my understanding of science topics 80% agree 88% agree By the conclusion of class, I usually feel I understand the 61% agree 72% agree chemistry concept of that lesson I do not benefit from the questions and discussions in class 86% disagree 96% disagree I do not find the notes and lecture in class useful 86% disagree 100% disagree
According to student responses, 76% of students in Class B (Simulation first) expressed that there were more frequent opportunities to generate scientific ideas in this chemistry class than in most other classes, whereas only 50% of students felt this way in Class A (traditional first).
This may suggest that students found that the TEMBS simulation encouraged generation of scientific ideas. Both classes strongly agree that peer discussion is valuable for their understanding of science topics. Students in both classes strongly disagree that they do not find discussions, notes and lectures in class useful.
86 Table 8: Analysis of Survey 2 Part 1
Statements Traditional Simulation First First Demonstrations of chemical phenomena are more effective for my learning 35 % agree 65 % agree than an interactive simulation to the same chemical phenomena. I become frustrated if a computer program does not respond according to my 30 % agree 60 % agree expectations. I believe educational computer programs can help me learn. 50 % agree 91 % agree There are more frequent opportunities to generate scientific ideas in this class 50 % agree 74 % agree than in most other classes. Peer discussion is valuable for my understanding of science topics. 60% agree 82 % agree It would aid my understanding if the simulations in class were paired with a 55% agree 69% agree concrete demonstration of a lab activity wherever possible. Having us generate, evaluate, and modify relationships is valuable to my 65% agree 74% agree understanding of the concepts in chemistry. I have to modify some of the initial relationships I generated in class. 40% agree 70% agree An important advantage of computer simulations is that they make 55% agree 70% agree unobservable processes in chemistry more explicit to me. Teacher guidance is necessary for the effective use of simulations 60% agree 78% agree
Survey 2 took place after the entire sequence of instruction. According to the survey, 65% of students using simulation first compared to 35% in the traditional first class said that demonstrations of chemical phenomena were more effective for their learning than an interactive simulation to the same chemical phenomena. This may suggest that 65% of students in Class B
(Simulation first) did not find the simulation to be as useful as a demonstration. Only 35% of students in Class A agreed that a demonstration was more effective than an interactive simulation.
This finding may suggest that most students in Class A did not find demonstrations to be more effective than an interactive simulation. Twice as many students in Class B compared to Class A found it frustrating when a computer program did not respond according to their expectations.
Seventy eight percent of students in Class B found that teacher guidance was necessary for effective use of computer simulation compared to 60% of students in Class A. This reveals that in
87 general most students find that teacher guidance is necessary for the effective use of computer simulations, but more students (18%) in the simulation first class expressed that teacher guidance was necessary.
Seventy percent of students in Class B found that computer simulations made unobservable processes in chemistry more explicit to them, compared to only 55% of students in Class A.
Ninety-one percent of the students who interacted with the simulation first believed that educational computer programs could help them learn compared to only 51% of students who received traditional first. Seventy percent of students who interacted with the simulation first compared to 40% in traditional first found that they had to modify some of the initial relationships generated in class.
Analysis of Survey 2 Part 1 shows how students rank where greatest learning happens (Top Three):
Traditional First 1. Teacher Discussions with students during class. 2. Classroom demonstrations. 3. Classroom simulations.
Simulation First 1. Teacher Discussions with students during class. 2. Classroom demonstrations. 3. Reading the textbook.
Finding 6. According to Survey 2 Part 2 Students found the Prediction feature, the Analogy feature and the graphs to be the most effective.
The students in the traditional first class found the following features of the TEMBS simulation to be the most interesting: (1) Being able to see the effects of stress at the molecular
88 level (2) Its ability to be modified (3) The visual representation of the equilibrium (analogy) (4)
The graphical explanations and (5) Having the ability to control the volume, concentration, pressure, etc. According to the survey, students enjoyed being able to test the different features and answering the prediction pop up questions. Students also reported that the simulation helped them answer the test questions better.
According to Survey 2 Part 2, the features of the TEMBS simulation that students found most interesting were motion diagrams in the Molecular view, “since you could see them changing in front of your eyes and it was hands-on making it easier to understand concepts”. They found that the simulation provided them with a better understanding of the concentration effects.
Students suggested that in the viewing panel the molecules should not be moving outside the screen, but instead should bounce off the sides so the simulation could be periodically stopped and students could count each species. Students also recommended more prediction questions.
Students recommended that TEMBS simulation Version 1 could be improved if students got to put in their own equations and see the effects of different stresses.
Finding 7. Evidence of Common Misconceptions in Chemical Equilibrium
The interviews during the project revealed several misconceptions mentioned earlier in the
Literature Review. The most common misconception that emerged was a compartmentalization view of chemical reactions, where students separate reactants from products and assume that stresses are applied to either reactants or products. The following dialogues from the interviews are examples of compartmentalization view. The following interview transcripts were in response
89 to the teacher’s questions such as, “What analogy did your group use to explain Le Chatelier’s principle?”
S2 - …to increase temperature we light one house on fire and they all run to the other one… for safety reasons. (Compartmentalization)
S1- Initially…we didn’t really have any big ideas…we were thinking of simple chemicals or formulas…and working with that but we didn’t like that too much so…we had ideas like its an analogy…of a party in two rooms and people mingling within the two rooms and the different stresses make people go from one room to another…
S2 – one room is reactants and one room is products…so heat would make them change to the other room…and pressure changes would involve taking reactants or products (compartmentalization).
S1- Basically we have two panels with circles on each side represented by two different colours…so we show how as we add circles to one side, the number of circles change on the other side…so this will be the first stress, concentration. (Compartmentalization view)
T- Two stresses only…Now as a student if you are presenting this to me…your way of representing the equilibrium and how things are changing to explain the concept is good. The stages are shown really well. The two rooms that were mentioned, two separate rooms, if we were to show that or apply that to a reaction at equilibrium, this may make me think that reactants and products are separate from each other…as you have mentioned two separate rooms, right? (Compartmentalization)
S3- Yes, there are two separate rooms. T- So does this mean that we are subjecting reactants and products to stresses separately?
S2- No, well…when we add the concentration that stress is subjected just to the reactants. T- What about temperature?
S2- The heat one is subjected to both.
T- Now you have the equilibrium established and I can see you are applying heat to the reaction (pointing to the diagram) and you have drawn heat here. Why is it only on the reactant side? You have drawn your reactants and products in two separate boxes? Why is that?
S1- Just so that the class can compare better because if it is in one huge thing then it would not be as obvious…and this way…they can see here are the products…and here are the reactants…
90 T- As a student I would see it as two different reactions taking place in two separate containers. What do you think?
S1- We can explain to them…that to make it clear…we have reactants here and products in a different container so that you can see how their concentrations are increasing…make it easier for you to see and count. T- But I would still be confused. Since you are showing them in two different colours, do you still need to keep them in separate boxes?
S1- Not really…that makes sense. T- What changes are you going to make to your project now?
S2- Put reactants and products on one container and apply heat to both. T- Why?
S2- Since the stress is applied to the whole reaction
In addition to a compartmental view of chemical interactions, students also seemed to have the misconception that when reactant and product concentrations were equal then the reaction was at equilibrium. However, when the rates of the forward and reverse reactions are equal then the reaction is said to be at equilibrium. The following dialogue in the interview is an example:
S1- One of the stresses will be we are adding the reactant concentration (Reactant B – sad faces) add four additional sad faces, first picture, second picture some time passed…for the reaction to move forward and following that to show that equilibrium where the concentrations are equal again because the coefficients for all the concentrations of the reactions are just one…so our equilibrium will be when all our concentrations are equal. (Misconception – Concentrations equal does not necessarily mean at equilibrium) T- The equilibrium will be when all the concentrations are equal? Is that a requirement for a reaction at equilibrium?
S1- No it isn’t, it’s just for our reaction because we have coefficients as one for both our reactants and products…concentrations are constant for our equilibrium. (Student changes response to constant instead of equal)
The students were seen to hold on strongly to the compartmentalization view of chemical reactions prior to the second interviews. Upon completion of the project, however, most students were able to understand that reactants and products were not compartmentalized
91 and were subjected to the same stress. For example, when a stress, such as increasing pressure, is applied to an equilibrium system, students failed to understand that the change affected both reactants and products. Since the project was completed at the end of the instruction sequence and both classes received instruction in the traditional form and interacted with the simulation as well, students were found to change their misconceptions.
In this project that students carried out in class, students had drawn representations of reactants and products in separate compartments. In terms of the dynamic nature of equilibrium, the following conversation is an example showing that students were still treating reactants and products separately, but they seemed to understand the dynamic nature of chemical equilibrium, that forward and reverse reactions continue to take place at an equal rate:
S2- So like some people don’t like this party and some people don’t like that party and so an equal amount is changing, reverse and then forward. T- So you are showing me 5 people here and 6 people in the other party and…
S2- But the same amount of people are going back and forth. T- Same number of people are going back and forth?
S2- Yes, reaction rates are equal.
This conversation indicates that the students had a clear understanding of the concept of dynamic equilibrium. This conversation was part of the final interview at the end of the entire sequence of instruction. The following are additional examples of how students’ initial misconceptions changed over the duration of the interview.
S2- …and then in the second stage, the concentration is changing so there are some products and equilibrium is slowly being reached…and in the final stage equilibrium is established and the concentrations are now constant. T- How would you know that?
92 S2- We will show that the mole ratio is the same… T- Mole ratio is the same? What do you mean by that? Compared to what?
S2- Compared to what it was initially. S1- The same number of reactants and products… S3- I think we should also draw another stage exactly the same…like constant…to show there are no changes…so it’s constant…meaning equilibrium is reached…they will have the same number of molecules…so its staying constant. T- What is staying constant?
S3- The molecules…like three here and three here. T- What about the molecules are staying constant?
S3- The number of them so there are 3 here and 3 there. T- What do the numbers indicate? What quantity are we looking at?
S3- The forward and reverse rates should be equal. T- That’s one factor…what else tell us that the reaction has reached equilibrium?
S3- The concentrations are constant.
T- How do we know it’s at equilibrium? I can see here you have 5 green and 5 yellow. Is there any reason why you have the same numbers of A & B?
S2- I was going to show that if say one goes to green then one comes back to yellow. S3- This will show that the speed of change is same, i.e., rates are equal. T- That’s right. However I also see that you have the same numbers of A &B. Does this mean that the concentrations are equal?
S2- No…well the concentrations don’t need to be equal. T- How would we show that it is at equilibrium in terms of concentration?
S4- Well the concentration would be constant… T- So concentration must be constant, okay. Even though you are showing those numbers of molecules on both sides, you may want to include another slide…What would you show on the next slide in order to show its at equilibrium?
S2- We would show the same thing. T- What do you mean?
S2- We will have the same numbers of molecules on both slides. The next slide will be exactly the same as the earlier slide. T- Exactly! And that would make it clear to the students that the reaction is at equilibrium. Not the fact that concentrations must be equal but constant. What is your next stress?
T- In which diagram do we see that equilibrium has been established first before subjected to a stress?
S2- Here, when the concentration is constant.
T- Explain the effects of changes in temperature?
S2- When the temperature decreases there will be more ammonia produced…favours products…when the temperature increases…favours reactants.
93 T- Does the forward reaction stop then since it favours reactants?
S1- No…increase in temperature speeds up both the reaction rates, forward and reverse but favours reverse more so more reactants are produced. T – How are you changing the concentration?
S1- We are adding more N2…so there will be more NH3 produced. T- How would the new equilibrium concentrations of reactants and products compare to the previous equilibrium?
S1- Concentration of N2 will be higher…NH3 will also be higher…but H2 will be less? T- Why?
S2- Since we are adding more N2, the system will lower the concentration in order to achieve equilibrium again but this would be based on how much H2 is present to react…so it will decrease but it would still be higher than the previous concentration.
T- What about H2? S1- H2 will decrease because it will react with the added N2 to produce more NH3. T- Yes.
These examples indicate that students achieved a clear understanding of the concept of chemical equilibrium. As mentioned earlier, since this interview took place at the end of the entire sequence of instruction, students may have understood the concepts better through the simulation and this is affirmed by the post-test results. The prediction questions in the simulation activity sheet and the prediction feature in the simulation may have encouraged students to test their hypothesis and possibly modify them.
In summary, as shown by an analysis of the post-test results, traditional instruction and then simulation was a more effective instructional sequence in enhancing student understanding of the concept of chemical equilibrium than an instructional sequence where the simulation was introduced first and then followed by traditional teaching. Learning through interaction with the simulation and learning through traditional means was found to achieve the same outcomes since the ANOVA of the mid-test results were found to be not significantly different. The post-test results for the two classes were significantly different, indicating the simulation was more effective
94 in addressing student misconceptions when it was introduced after traditional instruction rather than when it was used to begin instruction.
It is plausible that traditional instruction provided students a necessary background on the concept of chemical equilibrium and encouraged students to generate mental models of the concept of chemical equilibrium, which students then evaluated while interacting with the computer simulation. The questions in the simulation activity sheet also asked students to make predictions, test their predictions and evaluate their responses. Alternate conceptions that students in class A who experienced traditional instruction first may have been addressed when they interacted with the simulation as shown by the improvement in the post-test scores. The simulation was found to be more effective for this group (students in class A-traditional first). It is further hypothesized that the students were able to evaluate their initial mental models when they interacted with the simulation and modified them based on the multiple representations on the simulation and achieved a clear understanding of the concept of chemical equilibrium. This is affirmed by the improved average score of class A students on the post-test.
However, students in Class B (simulation first) interacted with the simulation without the same theoretical background, which in theory may have accounted for their lower scores on the post-test. Class B may not have performed as well because they were not able to make a connection between what they discovered through the simulation and their previous knowledge on the concept. As mentioned earlier, students were only introduced to the concept of chemical equilibrium in this study for the first time. The fact that reactions can go forward and in reverse is a completely new concept to students. Both classes of students were given the same amount of time to work on the simulation; it may be possible, however, that students would have performed
95 better on the tests if they had more time with the simulation. Students in both classes still had misconceptions as evidenced in the transcripts from the interviews during the equilibrium project after both traditional and simulation based instruction. However, there were seven groups of students, three to four students per group, in each class and the transcripts that have been reported earlier are only those groups that continued to hold on to their misconceptions. Students were expected to achieve specific learning outcomes from this unit on chemical equilibrium and therefore a theoretical background may have been necessary for students to relate to as they interacted with the simulation.
In terms of the simulation itself, according to the surveys, students from both classes found all the features of the TEMBS simulation to be very useful, but they found the dynamic analogy and prediction questions to be the most effective for their learning. They also liked the ability to manipulate the variables in the simulation. Students were not just clicking without thinking.
According to MBTL theory, one hypothesis could be that the students were able to test their mental models using the simulation.
The same outcome may be possible had a different simulation been used. Further research with a different simulation may or may not suggest this. Computer simulations that have an analogy view, like TEMBS simulation, afford special learning in science. That analogies increase student understanding in chemistry (Gabel & Sherwood, 1983) was also reinforced according to the interviews and surveys in this study. The class that interacted with the simulation first had the opportunity to “explore” the concept, which some students did, but most students were confused because they were acquiring information they could not relate to. In this study, the students were provided a simulation activity sheet with instructions and the teacher guided them through the
96 process. The simulation activity sheet also encouraged generation of models, asking students to draw diagrams showing a system at equilibrium and how the system would respond to changes in temperature, etc. Similar results may not have been achieved without the simulation activity sheets. The activity sheets also encouraged students to evaluate and modify their models of chemical equilibrium asking them to make predictions before manipulating the variables on the simulation.
Summary
In this Chapter the findings were as follows: (1) Both classes had similar achievement levels on the pre-test; (2) Traditional first or simulation first achieve similar learning outcomes on the equilibrium mid-test; (3) Overall improvement in student understanding on the equilibrium post- test; (4) Teacher discussions in class as top most effective learning experience according to equilibrium survey 1; (5) According to Survey 2 Part 2 students found the prediction feature, the analogy feature and the graphs to be most effective and; (6) Evidence of common misconceptions in chemical equilibrium. The last chapter, Chapter 5, consists of conclusions and implications for teaching.
97 CHAPTER FIVE
CONCLUSION AND IMPLICATIONS FOR TEACHING
Chemistry is considered a difficult subject for most students, yet it is one of the most important branches of science. The abstract nature of the chemical concepts, such as chemical equilibrium, and the inability to visualize at the molecular level makes it difficult for many students. The computer simulation used in this study, the TEMBS simulation, was based on an established learning theory framework called GEM cycle model based learning. To respond to research question 1, the Equilibrium mid-test and post-test results were analyzed. This study helped to identify how computer simulations with multiple representations such as TEMBS simulation can be incorporated into the curriculum and when it can be most effectively used for instruction. The computer simulation appeared to contribute to student learning and the evidence that suggested this was the post-test results. Based on the post-test results, student interaction with the computer simulation seemed to help students’ improve their understanding of the concept of chemical equilibrium. This finding supports other research on the TEMBS simulation (Khan &
Chan, 2010; Khan, 2007; Trey & Khan, 2007) and other research on similar simulations that utilize multiple representations (Colella, 2000; Khan, 2008; Kozma, 2000; Piburn, 2005; Steiff &
Wilensky, 2003; Wu & Shah, 2004).
Simulations alone will not help explain concepts. But, according to my research, simulations achieve the best results when introduced after traditional forms of instruction. To more specifically respond to research question 2, the Equilibrium mid-test and post-test results were analyzed. According to the ANOVA test, there was not a significant difference between the two
98 classes on their Pre-test and Mid-test. The mid-test, which occurred after the traditional form of instruction in one class, and after the TEMBS simulation in the other class, suggests that traditional method of teaching Le Chatelier’s Principle achieves similar learning outcomes compared to beginning instruction with a computer simulation. However, from the post-test results there is a significant difference between the two classes. The class that received traditional instruction prior to interaction with the simulation performed significantly better than the class that used the simulation before traditional instruction. It seems to be a clear indication from the data that students who received traditional instruction first had a stronger grasp of the theoretical background on the concept, reinforced through lecture and laboratory session, and were therefore able to relate the concepts and observe the applications on the TEMBS simulation better.
Although computer simulations that have multiple representations may help to address student misconceptions, I believe students may first need to become aware of the concept through lectures and class discussions. Only then computer simulations can be more effective in addressing misconceptions and improve students’ understanding of abstract concepts.
According to the survey results, I also found that students ranked the top three learning strategies to be as follows:
Traditional First
1. Teacher discussions with students during class.
2. Classroom demonstrations.
3. Classroom simulations.
Simulation First
1. Teacher discussions with students during class.
99 2. Classroom demonstrations.
3. Reading the textbook.
Both classes suggested teacher discussions to be vital for student learning, according to the students surveyed. Teacher discussion is an engaging process, since through the discussions the students can potentially notice how their models evolve as a result of the discussions generated.
The TEMBS simulations itself may have promoted understanding of chemical equilibrium systems by supporting the generation of more scientifically accurate models of chemical equilibrium.
According to the survey, 91% of students in class B (simulation first) believed that educational computer programs could help them learn and 70% of the students found computer simulations to make unobservable processes in chemistry more explicit.
The TEMBS simulation was helpful in addressing several misconceptions that students hold in chemistry such as: (1) Compartmentalization view and (2) The dynamic nature of chemical equilibrium (Gussarsky & Gorodetsky, 1990). Using computer simulations can potentially support students’ evolution of their mental models of abstract concepts as they generate, evaluate and modify their models. Computer simulations promote students’ understanding of unobservable phenomena in chemistry by integrating multiple representations of the same phenomena.
According to Khan (2010), findings show that the best time to introduce GEM with technology (T-GEM) is before concepts are introduced. Only after T-GEM were students instructed to use the textbooks to elaborate on what they learned. Simulation technology was integrated in every stage of GEM. Students were organized in pairs or groups of three at each terminal. The teacher was involved in every stage of the GEM learning cycle. The teacher
100 asked students to make predictions and encouraged them to modify their models. In my research, however, the students worked individually on the TEMBS simulation. The teacher did not interact with the students during the simulation phase for both the classes and only provided assistance with the operation of the simulation when needed. The teacher did not ask students to make predictions, rather students were encouraged to predict through the simulation and the simulation activity sheet. Also in the Khan (2010) study participants were first year undergraduate students whereas participants in this study were high school students. I speculate that we may pay attention to these differences in the two studies, which may account in part for the different findings.
The traditional form of instruction that is most effective as suggested by students according to the surveys is teacher discussions. It is a conceivable cognitive process that through teacher discussions, students could generate their mental models of the concept and then if a simulation with multiple representations is introduced, the students can evaluate and modify their mental models. The simulation therefore becomes a learning method rather than a game. I hypothesize that the class that interacted with the simulation first had the opportunity to “explore” the concept. Some students did, but most students were confused because they were acquiring information they could not relate to. In this study the students were provided a simulation activity sheet with instructions and the teacher guided them through the process. The simulation activity sheet also encouraged generation of models, asking students to draw diagrams showing a system at equilibrium and how the system would respond to changes in temperature, etc. The simulation activity sheet also asked students to make predictions before manipulating the variables on the simulation. Computer simulations that have an analogy view, like TEMBS simulation, afford
101 special learning in science. Research suggests that analogies increase student understanding in chemistry (Gabel & Sherwood, 1983), and this was also suggested according to the interviews in this study.
In terms of recommendations, I recommend that technologists and software developers collaborate with teachers and curriculum developers to design educational computer simulations with multiple representations. Multiple representations, such as those in the TEMBS simulation, allow students to generate, evaluate and modify their models of a concept. Before teaching a concept such as chemical equilibrium, I would recommend that teachers research the literature on alternate conceptions that students bring to class. They should then use a simulation as one effective teaching strategy that would help to address those alternate conceptions. Based on my research, I would recommend that simulations like
TEMBS be introduced after a lecture and discussion session about the concept between the teacher and the students. I would further recommend that technologies such as computer simulation be used by students along with an activity sheet with step-by-step instructions and questions, such as those inspired by MBTL (e.g., GEM), that foster deep conceptual understanding.
This research may be important to teachers who may be concerned that computer simulations may not deliver as much content or information as traditional means of instruction. It may also encourage teachers who hesitate to use computer simulations to teach chemistry concepts. This research is important to curriculum developers since they can guide new teachers on how to incorporate technology into their classrooms.
102 Future research is needed to examine what form of traditional instruction is more effective than the other forms of traditional instruction when integrated with a computer simulation. Since there was only one lab and three lessons of lectures and discussions, it may be possible that the lecture and discussion sessions were more effective than the lab. An implication of this study for science educators and educational technologists is that computer simulations such as TEMBS simulations, which utilize multiple representations including chemical formula, slider, graph, description, prediction, molecular and dynamic analogy views, can assist students in their understanding of abstract concepts such as Le Chatelier’s
Principle.
103 BIBLIOGRAPHY
Barke, H-D., Hazari, A., & Yitbarek, S. (2009). Misconceptions in chemistry: Addressing perceptions in chemical education. Berlin: Springer-Verlag.
Benford, R. & Lawson, A. (2001). Relationships between effective inquiry and the development of scientific reasoning skills in college biology labs (pp. 1-72). ED456157.
Blauch, D. (1998). Le Chatelier’s Principle: Retrieved July 10, 2010 from http://www.chm.davidson.edu/java/LeChatelier/LeChatelier.html
British Columbia. Ministry of Education.(2005). Science Integrated Resource Package 2005. Retrieved April 15, 2005, from [http://www.bced.gov.bc.ca/irp/chem1112/ch]
Chan, V. & Khan, S. (2009). Dynamic computer analogies and conceptions of chemical equilibrium. In T. Bastiaens et al., (Eds.), Proceedings of World Conference on E-Learning in Corporate, Government, Healthcare, and Higher Education 2009. Chesapeake, VA, pp. 864-873.
Chi, M. T. H., & Bassock, M. (1989). Learning from examples via self-explanations. In L. B. Resnick (Ed.), Knowing, learning, and instruction: Essays in honour of Robert Glaser (pp. 251-282). Hills dale, NJ: Erlbaum.
Clement, J., & Oviedo, M. C. N. (2003). Model evolution: A strategy based on model based teaching and learning theory. A paper presented at the AERA Conference, Chicago, IL on April 21-25, 2003.
Colella, V. (2000). Participatory simulations: Building collaborative understanding through immersive dynamic modeling. Journal of the Learning Sciences, 9(4), 471-500.
Coll, R. K., & Treagust, D. F. (2003). Investigation of secondary school, undergraduate, and graduate learners’ mental models of ionic bonding. Journal of Research in Science Teaching, 40(5), 464-486.
Davis, R. E., Metcalfe, H. C., Williams, J. E., & Castka, J. E. (2002). Shifting Equilibrium. In Grayson, M., Kilpatrick, M., & Benner, J. A. (Eds.), Modern Chemistry (p. 562). United States of America: Holt, Rinehart & Winston.
Duit, R. (1991). On the role of analogies and metaphors in learning science. Science Education, 75 (6), 649-672.
104 Eilam, B. (2004). Drops of Water and of Soap Solution: Students’ Constraining Mental Models of the Nature of Matter. Journal of Research in Science Teaching, 41(10), 970-993.
Erduran, S. (2001). Philosophy of chemistry: An emerging field with implications for chemistry education. Journal of Chemical Education, 10, 581-593.
Gabel, D. & Sherwood, R. (1983). Effect of using analogies on chemistry achievement according to Piagetian level. Science Education, 64(5), 709-716.
Gentner, D., & Gentner, D. (1983). Flowing waters and teeming crowds: Mental models of electricity. In D. Gentner & A. L. Stevens (Eds.), Mental models (pp. 99-129). Hillsdale, NJ: Erlbaum.
Griffiths, A. K., & Preston, K. R. (1989). Grade 12 students’ Misconceptions relating to fundamental characteristics of atoms and molecules. Journal of Research in Science Teaching, 29(6), 611-628.
Goodwin, A. (2001). Teachers’ continuing learning of chemistry: Implications for pedagogy. Paper presented at the ‘Variety in Chemical Education Conference, University of Lancaster, September 18, 2001. Retrieved April 15, 2005, from [http://scholar.google.com].
Gussarsky, E., & Gorodetsky, M. (1990). On the concept “Chemical Equilibrium”: The associative framework. Journal of Research in Science Teaching, 27, 197-204.
Khan, S. (2005). Le Chatelier’s Principle TEMBS [Computer software]. Vancouver, BC: Technology-enhanced Model-based Science Group, University of British Columbia. Retrieved March 26, 2005 from http://www.ca.ubc.ca/~ferstay/tembs_2005Mar26.zip. Or by contacting [email protected]
Khan, S. (2005). Constructing visualizable models in chemistry. Presented in S. Khan (chair), Visual Representations in Model Based Learning Symposium, Annual Meeting of the American Educational Research Association (AERA), Montreal, PQ. pp. 1-29.
Khan, S. (2007). Model-based inquiries in chemistry. Science Education, 91(6), 877-905.
Khan, S. (2008). Model-based teaching as a source of insight for the design of a viable science simulation. Technology, Instruction, Cognition, and Learning, 6(2), 1-16.
Khan, S. (2009). What if scenarios for testing student models. In J. K. Gilbert, (Series Ed.), Models and modeling in science education, Volume 2 (pp. 141-152). Netherlands: Springer Publishing.
105 Khan, S. (2009). Co-construction and model evolution in chemistry. In J. K. Gilbert, (Series Ed.), Models and modeling in science education, Volume 2 (pp. ?-?). Netherlands: Springer Publishing .
Khan, S. & Chan, V. (2010, submitted). Dynamic computer analogies revisited (pp. 1-41).
Kousathana, M., & Tsaparlis, G. (2002). Students’ errors in solving numerical chemical-equilibrium problems. Chemistry education: Research and practice in Europe, 3, 5-17. Retrieved April 15, 2005, from [http://scholar.google.com].
Kozma, R. B., Russell, J., Johnston, J., & Dershimer, C. (1990). College students’ understanding of chemical equilibrium. A Paper presented at the Annual Meeting of the American Educational Research Association, Boston, MA.
Kozma, R. B., & Russell, J. (1997). Multimedia and understanding: Expert and novice responses to different representations of chemical phenomena. Journal of Research in Science Teaching, 34, 949-968.
Kozma, R. (2000). The use of multiple representations and the social construction of understanding in chemistry. In M. Jacobson & R. Kozma (Eds.), Innovations in science and mathematics education: Advanced designs for technologies of learning (pp. 11-46). Mahwah, NJ: Erlbaum.
Krajcik, J. (1991). Developing students’ understanding of chemical concepts. In S. Glynn, R. Yeany, & B. Britton (Eds.). The psychology of learning science (pp. 117-148). Hillsdale, NJ: Lawrence Erlbaum Associates.
Marek, E. A. (1986). Understanding and misunderstandings of biology concepts. American Biology Teacher, 48(1), 37-40.
Marek, E. A. & Bryant, R.J. (1991). On Research: Your teaching methods may influence your students’ understanding of common science concepts. Science Scope, 14(4), 44-45, 60.
Marx, R.W., Blumenfield, P. C., Krajcik, J. S., Fishman, B., Soloway, E., Geier, R., & Revital, T. T. (2004). Inquiry-based science in the middle grades: Assessment of learning in Urban systemic reform. Journal of Research in Science Teaching, 41 (10), 1063-1080.
Metz, K. (2004). Children’s understanding of scientific inquiry: Their conceptualization of uncertainty in investigations of their own design. Cognition and Instruction, 22(2), 219-290.
Nakleh, M. B. (1992). Why some students don’t learn chemistry. Journal of Chemical Education, 69, 191-196.
106 Nakleh, M. B. (1993). Are our students conceptual thinkers or algorithmic problem solvers? Journal of Chemical Education, 70, 52-55.
Nakleh, M. B., & Mitchell, R. C. (1993). Concept learning versus problem solving. Journal of Chemical Education, 70,190-192.
Nersessian, N.J. (1992). How do scientist think? Capturing the dynamics of conceptual change in science. In R. N. Giere (Ed.), Cognitive Models of Science, Volume 15 (pp.3-44). Minneapolis: University of Minnesota Press.
Nicoll, G. (2003). A qualitative investigation of undergraduate chemistry students’ macroscopic interpretations of the submicroscopic structure of molecules. Chemical Education Research, 80(2), 205-212.
Osborne, R. J.; Cosgrove, M. M. (1983). Children’s conceptions of the changes of state of water. Journal of Research in Science Teaching, 20, 825-838.
Ozmen, H. (2004). Some student misconceptions in chemistry: A literature of chemical bonding. Journal of Science Education and Technology, 13(2), 147-160.
Pedrosa, M. A., & Dias, M. H. (2000). Chemistry textbook approaches to chemical equilibrium and student alternative conceptions. Chemistry Education: Research and Practice in Europe, 1, 227-236. Retrieved April 15, 2005, from [http://scholar.google.com]
Peterson, R. F.; Treagust, D. F. (1989). Grade-12 students’ misconceptions of covalent bonding and structure. Journal of Chemical Education, 66, 459-460.
Quilez, J. (2004). A historical approach to the development of chemical equilibrium through the evolution of the affinity concept: Some educational suggestions. Chemistry Education: Research and Practice, 5(1), 69-87. Retrieved April 15, 2005, from [http:/scholar.google.com]
Rea-Ramirez, M.A. (1998). Model of Conceptual understanding in human respiration and strategies for instruction. Unpublished doctoral dissertation, Univeristy of Massachusetts, Amherst.
Roth, W-M. (1993). The development of science process skills inauthentic contexts. Journal of Research in Science Teaching, 30(2), 127-152.
Shapiro, M.A. (1985). Analogies, visualization and mental processing of science stories. Presented to the Information Systems Division of the International Communication Association, Honolulu, HI, 1-37.
107 Spier-Dance, L., Khan, S., & Dance, N. (2005). Textbooks and student understanding in introductory undergraduate chemistry. In Proceedings of the Annual Meeting of the National Association for Research in Science Teaching (NARST), Dallas, TX. pp. 1-28.
Sprague, D., Trey, S., Pillay, S., & Khan, S. (2005). How computer simulations can assist model generation in students: Encouraging students to think before the click. In Proceedings of the ED-MEDIA 2005, World Conference on Educational Multimedia, Hypermedia & Telecommunications, Montreal, Canada, pp. 1-8.
Steiff, M., & Wilensky, U. (2002). ChemLogo: An emergent modeling environment for teaching and learning chemistry. Paper presented at the fifth biannual International Conference of the Learning Sciences: Northwestern University, Evanston, IL 60208. Retrieved April 15, 2005 from http://ccl.northwestern.edu/papers/chemlogo/
Steiff, M., & Wilensky, U. (2003). Connected chemistry-Incorporating interactive simulations into the chemistry classroom. Journal of Science Education and Technology, 12 (3), 285-302.
Teichart, M. A., & Stacy, A. M. (2002). Promoting understanding of chemical bonding and spontaneity through student explanation and integration of ideas. Journal of Research on Science Teaching, 39, 464-496.
Trey, L. & Khan, S. (2007). How science students can learn about unobservable phenomena using computer-based analogies. Computers and Education, 51(2), 519-529.
Treagust, D. F., Chittleborough, G., & Mamiala, T. L. (2002). Students’ understanding of the role of scientific models in learning science. Journal of Science Education, 24,357-368.
Turkmen, H. (2006). What technology plays supporting role in learning cycle approach for science education. Turkish Online Journal of Educational Technology, 5(2), 71-76.
Turkmen, H. & Usta, E. (2007). The role of learning cycle approach overcoming misconceptions in science. Journal of Kastamonu Education, 15(2), 491-500.
Volland, W. (1998). Le Chatelier’s Principle: What happens to an equilibrium when conditions change. Retrieved July 30, 2009 from http://www.800mainstreet.com/7/0007-008- le_chatelier.html.
Wallace, C.S., & Kang, N-H. (2004). An investigation of experienced science teachers’ beliefs about inquiry: An examination of competing belief sets. Journal of Research in Science Teaching, 41(9), 905-935.
Webb, N. M. (1989). Peer interaction and learning in small groups. International Journal of Educational Research, 13, 21-40.
108
Webb, N. M., Troper, J. D., & Fall, R. (1995). Constructive activity and learning in collaborative small groups. Journal of Educational Psychology, 87(3), 406-423.
Wilensky, U. (1999). NetLogo [Computer software]. Evanston, IL: Center for Connected Learning and Computer Based Modeling, Northwestern University. Retrieved on July 10, 2010 from http://ccl.northwestern.edu/netlogo.
Wu, H., Krajcik, J.S., & Soloway, E. (2001). Promoting understanding of chemical Representations: Students’ use of visualization tool in the classroom. Journal of Research in Science Teaching, 38(7), 821-842.
109 APPENDICES Appendix A: Principal Letter
Sharmila Pillay
April 25, 2005
The Principal, ______Secondary School,
Dear Mrs. ______,
I would like to request your permission to conduct a research study, as part of my Masters’ thesis program, in my Chemistry 12 classes. My research is on the use of Computer simulations in teaching concepts in Chemistry. I will be specifically looking at the concept of Chemical Equilibrium and Le Chatelier’s Principle. This area has been identified as one of the most difficult concepts for students to understand. The research is based on using simulations in chemistry to allow students to generate mental models that they can use to develop a better understanding of concepts (Please see the Research Proposal for a detailed description of this). The anticipated time of research would be MAY-JUNE, 2005, pending approval from Behavioural Research Ethics Board, University of British Columbia (604-827 5112). I have received an approval from the Surrey School Board (Please see approval letter attached). The purpose of this study is to explore student understanding of unobservable phenomena in science and consider the ways in which understanding can be fostered with the use of new media technologies in the classroom. The simulation that will be used in this study is based on Le Chatelier’s principle and its application in the chemical equilibrium unit. This unit is an important part of the course content in the chemistry 12 curriculum as it contributes towards the understanding of solubility equilibrium and acid base equilibrium. Student participation in this research will not affect their grades in any way. To insure this, consent forms will be collected, placed in a sealed envelope, and locked in a secure cabinet by a volunteer teacher, and placed the Science Prep room. Once the envelopes are in the cabinet it will not be opened again until after grades have been posted. This would allow students if they change their minds after having engaged in all of the class/research experiences to decide if they still want their data to be used in the research. Student participation level will not be affected negatively in any way. During the study, I may audio record the interviews that will take place at three different stages of a project that students will work on in-groups. The interviews will be
110 about 15-20 minutes long. The questions generated from the interviews are designed to assist in the evolution of students’ project. Students may ask that the recording device be disabled at any time or state that they do not wish to be recorded at all. Students will be given student consent forms and parent consent forms two weeks prior to the study. If the student or the parent had not consented to participating in this study then the students’ recorded voice and all recorded data will be deleted from the data set later. Students will be informed that their participation of lack thereof will not affect their grades in class. Students will also be asked to complete two survey forms. Each survey form will take about 15-20 minutes. Each survey form will be given at two different stages of the study, one at the beginning and one at the end of the project. Students will be given a pre-test, a mid-test and a post-test as part of the activities involved in the class. The pre-test will be administered after a primer (introduction) of Le Chatelier’s principle. The mid-test will be given after further instruction on chemical equilibrium, either through lecture and labs or after the simulation. The post-test will be given after completing both forms of instruction, i.e. simulation and lecture. All the activities in this study will be carried out during class time. Part of the equilibrium project will be done during tutorials after school. The complete study will take place over three weeks of instruction. Any information resulting from this study will be kept strictly confidential, and student identity will be kept completely anonymous. Students will not be required to use their names on the surveys or the tests. Confidentiality will be preserved with the use of false numerical identifiers instead of names of participants. The tests will have numerical identifiers and will be distributed by a colleague prior to a test. The volunteer teacher will be assigning students their numerical identifiers. Students will be using their numerical identifiers on all tests and activities. Students will be informed that participation in this study is entirely voluntary. I will be the only person present in the class during the study. As a research participant, students will have the right to access all data transcriptions upon request. They may refuse to participate or withdraw from the study at any time. Student participation or lack thereof will in no way affect their grade or class standing. The volunteer teacher will remove all non-participants’ from the data set and recorded interviews. The school will not be identified at any point in the dissemination of this data. If you have any questions or desire further information with respect to this study (including questions about the procedures used) you may contact me directly at school. Please find enclosed a copy of parent consent form, student consent form, parent letter, computer simulation activity, pre test, mid-test, post test, students survey forms, and research plan. Please let me know if you require any other information.
Yours truly, ______
Sharmila Pillay, MA student in the Faculty of Education, UBC. ______Faculty Advisor
111 Dr. S. Khan Faculty of Education (University of British Columbia)
112
Appendix Bi: Parent Letter
April 24, 2005
Dear Parents/Guardians,
I would like to conduct a research experiment, as part of my Masters’ thesis program, on how computer simulations can be used in Chemistry 12 to help improve student’s understanding of two of the major topics in the Chemistry 12 curriculum - the concept of Chemical Equilibrium and Le Chatelier’s Principle. The benefits of using these computer simulations will be observed in the classroom and students will apply their learning on the tests given. The tests given will include questions from Chemistry 12 Provincial Examinations and will serve as good indicators of student learning. I have found that students have great difficulty in understanding and applying Le Chatelier’s Principle therefore my research team has developed a software program that our students can use. I will be using this simulation to identify ways to make the program more useful for the students. The purpose of this study is to explore student understanding of unobservable phenomena in science and consider the ways in which understanding can be fostered with the use of new media technologies in the classroom. The simulation that will be used in this study is based on Le Chatelier’s principle and its application in the chemical equilibrium unit. This unit is an important part of the course content in the chemistry 12 curriculum as it contributes towards the understanding of solubility equilibrium and acid base equilibrium. Student participation in this research will not affect their grades in any way. To insure this, consent forms will be collected, placed in a sealed envelope, and locked in a secure cabinet by a volunteer teacher, and placed the Science Prep room. Once the envelopes are in the cabinet it will not be opened again until after grades have been posted. This would allow students if they change their minds after having engaged in all of the class/research experiences to decide if they still want their data to be used in the research. Student participation level will not be affected negatively in any way. During the study, I may audio record the interviews that will take place at three different stages of a project that students will work on in-groups. The interviews will be about 15-20 minutes long. The questions generated from the interviews are designed to assist in the evolution
113 of students’ project. Students may ask that the recording device be disabled at any time or state that they do not wish to be recorded at all. Please find attached a parent consent form. If you or your child do not consent to participating in this study then the students’ recorded voice and all recorded data will be deleted from the data set later. Students will also be asked to complete two survey forms. Each survey form will take about 15-20 minutes. Each survey form will be given at two different stages of the study, one at the beginning and one at the end of the project. Students will write a pre-test, a mid-test and a post-test as part of the activities involved in the class. The pre-test will be administered after a primer (introduction) of Le Chatelier’s principle. The mid-test will be given after further instruction on chemical equilibrium, either through lecture and labs or after the simulation. The post-test will be given after completing both forms of instruction, i.e. simulation and lecture. All the activities in this study will be carried out during class time. Part of the equilibrium project will be done during tutorials after school. The complete study will take place over three weeks of instruction. Any information resulting from this study will be kept strictly confidential, and student identity will be kept completely anonymous. Students will not be required to use their names on the surveys or the tests. Confidentiality will be preserved with the use of false numerical identifiers instead of names of participants. The tests will have numerical identifiers and will be distributed by a colleague prior to a test. The volunteer teacher will be assigning students their numerical identifiers. Students will be using their numerical identifiers on all tests and activities. Students will be informed that participation in this study is entirely voluntary. I will be the only person present in the class during the study. As a research participant, students will have the right to access all data transcriptions upon request. They may refuse to participate or withdraw from the study at any time. Student participation or lack thereof will in no way affect their grade or class standing. There are no known risks to participating in this study. If you have any questions or desire further information with respect to this study (including questions about the procedures used) you may contact me directly at school.
Yours truly,
______Mrs. S. Pillay (MA Student in the Faculty of Education, UBC.)
114 Appendix Bii: Parent Consent Form
PARENT INFORMED CONSENT FORM
USING SIMULATIONS IN CHEMISTRY 12 TO GENERATE MODEL-BASED LEARNING OF ABSTRACT CONCEPTS SUCH AS LE CHATELIER’S PRINCIPLE
Principal Investigator: Dr. S. Khan, Faculty of Education, Department of Curriculum Studies, University of British Columbia. Telephone: 822-5296. E-mail: [email protected]
Purpose: The purpose of this study is to explore student understanding of unobservable phenomena in science and consider the ways in which understanding can be fostered with the use of new media technologies in the classroom. The results from this study will be used towards my MA thesis.
Introduction: I would like to seek your consent in your child’s participation in research on classroom activities as part of an action research. The activities are related with the course content covered in the unit, Chemical Equilibrium. The principal investigator is a researcher from the University of British Columbia. The results of this study will be shared with the principal investigator. However during the instructions and activities in class I will be the only one present. As an action research project, your child will help towards generating research questions and guiding the research in ways that are important to their learning.
Study Procedures: I am searching for the ways in which conceptual understanding can be fostered in the science classroom. For this reason, I will be using a computer simulation on Le Chatelier’s Principle created by TEMBS Research group at the University of British Columbia. Le Chatelier’s Principle can be difficult to understand and to apply since it requires understanding at the molecular level. Although students are able to see macroscopic changes such as changes in colour and temperature they are not able to observe the changes at the molecular level and explain the changes that take place. The simulation has been designed to allow students to generate mental models that would assist them in understanding such abstract concepts. The simulation will be integrated with the regular class lecture, labs and exercises. To facilitate the learning, students will be assigned a project that they will work on in-groups. I will be interviewing them at three different stages of their project in order to guide them through the project. The questions from the interview will help the students generate a model of a chemical equilibrium that they will evaluate and modify as they progress through it. The conversation that will take place during the interviews will be audio-recorded so that I can evaluate the interviews and identify any alternate conceptions
115 students may have while learning Le Chatelier’s Principle. The study will take place over three weeks, May 23-June 13, 2005. Your permission is being sought concerning the audio recording during class. Participants will not be asked to do anything different or unusual in the lesson or in the way that they work. At the completion of the project, I will be very happy to play the audiotapes to the participants if they wish and the only people who will hear the tapes apart from the subjects in question will be the project investigators. No one else will hear the tapes. You will of course be free to opt out of the project at any time and such withdrawal will not affect your child’s grades or relationship with the school in any way. Apart from being audio-recorded, participants will not be treated in any way differently from non-participants who will be doing the same work, as they will be. The audiotaping will not affect the teaching of the normal lesson. The interviews are a normal part of the instruction. Students, who do not consent to being audio taped, will have their voices erased. This procedure will be carried out only after the course is completed and students have been assigned their final grades. With the volunteer teacher’s help, students who do not consent to audio recording will identify their voices and the volunteer teacher will delete their voices from the recordings. Your permission is also being sought for your child to complete a confidential, anonymous, initial assessment about scientific concepts that will be administered during normal classroom time. Confidentiality will be preserved on the initial assessment with the use of false numerical identifiers instead of names of student participants and their schools. Students will have the option of being identified by name instead of numerical identifier on the initial assessment if they so wish and with your approval.
Participation and Confidentiality: Any information resulting from this study will be kept strictly confidential. All data will be kept in a locked cabinet in the Science Prep Room at Enver Creek Secondary School. Any report that is written concerning this study will, preserve the complete anonymity of all participants and their school, unless a participant would like to be identified by name. I will only access the data after the course is over and students have been assigned their grades. At the end of the project, I may ask participating students whether I may use parts of the audiotapes at conferences such as the catalyst conference. You will be contacted at this later stage to give your permission. You and your child do not have to make that decision until you have heard the tapes. Contact: If you have any concerns about your rights or treatment as a human subject you may contact the Research Subject Information Line in the University of British Columbia Office of Research Services at 604-822-8598. If you have any other questions please contact me at School.
Consent: Please understand that participation in this project is entirely voluntary and that you and your child may refuse to participate or withdraw from the project at any time without jeopardy to class standing, grades, or relationship with the school. Please complete the attached Consent Form to indicate whether you do or do not give your consent for your child to participate in the classroom study. Keep this description of the study for your own reference and detach the consent slip below. You may submit your consent form along with your child’s consent form to the volunteer teacher.
Thank you.
116
Sharmila Pillay Chemistry Teacher Ma Student in the Faculty of Education
117
DETACH CONSENT SLIP AND RETURN TO VOLUNTEER TEACHER
PARENTAL /GUARDIAN CONSENT FORM Consent for classroom observations, audio recording, and initial assessment.
Please check the box indicating your decision:
I CONSENT to my child participating in the study as described in the above form.
I DO NOT CONSENT to participating in the project as described in the form.
I acknowledge that I have received a copy of this consent form.
Name (please print child’s name) Date:
Teacher’s name Div:
Parent/Guardian Signature
118 Appendix Ci: Student Participation Invitation
April 24, 2005
Dear …………,
As part of my Masters’ thesis program, I am inviting you to participate in an action research entitled “Using Simulations in Chemistry 12 to generate model-based learning of abstract concepts such as Le Chatelier’s Principle”. The principal investigator is a researcher from the University of British Columbia. Your involvement in this research will take the form of a project, interviews, surveys and tests. As an action research project, you will be able to help generate research questions and guide the research in ways that are important to your learning.
The purpose of this study is to explore student understanding of unobservable phenomena in science and consider the ways in which understanding can be fostered with the use of new media technologies in the classroom. I am inviting you to participate in this study because the simulation that will be used in this study is based on Le Chatelier’s principle and its application in the chemical equilibrium unit. This unit is an important part of the course content in the chemistry 12 curriculum as it contributes towards the understanding of solubility equilibrium and acid base equilibrium. Your participation in this research will not affect your grade in any way. To insure this, consent forms will be collected, placed in a sealed envelope, and locked in a secure cabinet by a volunteer teacher in the Science Prep room. Once the envelopes are in the cabinet it will not be opened again until after grades have been posted. This allows for you to change your mind after having engaged in all of the class/research experiences to see if you want your data to be used in the research. Your participation level will not affect you negatively in any way.
During the study, I may audio record the interviews that will take place at three different stages of a project that you will work on in groups. The interviews will be about 15-20 minutes long and the questions generated from the interviews are designed to assist in the evolution of your project. You may ask that the recording device be disabled at any time or state that you do not wish to be recorded at all. If you or your parent had not consented to participating in this study then your recorded voice and all recorded data will be deleted from the data set later. You will also be asked to complete two survey forms. Each survey form will take about 15-20 minutes. Each survey form will be given at two different stages of the study, one at the beginning and one at the end of the project. You will also be given tests, a pre-test, a mid-test and a post-test as part of the
119 activities involved in the class. The pre-test will be administered after a primer (introduction) of Le Chatelier’s principle. The mid-test will be given after further instruction on chemical equilibrium, either through lecture and labs or after the simulation. The post-test will be given after completing both forms of instruction, i.e. simulation and lecture. All the activities in this study will be carried out during class time.
Any information resulting from this study will be kept strictly confidential, and your identity will be kept completely anonymous. You will not be required to use your names on the surveys or the tests. Confidentiality will be preserved with the use of false numerical identifiers instead of names of participants. Furthermore, only researchers will have access to the data, and all data will be kept in locked filing cabinets. As a research participant, you have the right to access all data transcriptions upon request. You may refuse to participate or withdraw from the study at any time. Your participation or lack thereof will in no way affect your grade or class standing. There are no known risks to participating in this study.
If you have any concerns about your treatment or rights as a research subject you may contact the Research Subject Information Line in the University of British Columbia Office of Research Services at (604) 822-8598.
If you have any questions or desire further information with respect to this study (including questions about the procedures used) you may contact me directly at the school.
Yours sincerely,
Sharmila Pillay Chemistry Teacher MA student in the Faculty of Education, UBC.
Dr. Samia Khan Principal Investigator
120 Appendix Cii: Student Consent Form
STUDENT INFORMED CONSENT FORM
USING SIMULATIONS IN CHEMISTRY 12 TO GENERATE MODEL-BASED LEARNING OF ABSTRACT CONCEPTS SUCH AS LE CHATELIER’S PRINCIPLE
Principal Investigator: Dr. S. Khan, Faculty of Education, Department of Curriculum Studies, University of British Columbia. Telephone: 822-5296. e-mail: [email protected]
Introduction: I am inviting you to participate in research on your classroom activities as part of an action research. These activities are part of the course content on the unit, Chemical Equilibrium. The principal investigator is a researcher from the University of British Columbia. The results of this study will be shared with the principal investigator. However during this study I will be the only person present during instructions and activities in the classroom. As an action research project, you will be able to help generate research questions and guide the research in ways that are important to your learning.
Purpose: The purpose of this study is to explore student understanding of unobservable phenomena in science and consider the ways in which understanding can be fostered with the use of new media technologies in the classroom. The results from this study will be used towards my MA thesis.
Study Procedures: I am searching for the ways in which conceptual understanding can be fostered in the science classroom. For this reason, I will be using a computer simulation on Le Chatelier’s Principle created by TEMBS Research group. Le Chatelier’s Principle can be difficult to understand and apply since it requires understanding at the molecular level. Although you will be able to see macroscopic changes such as changes in colour and temperature you will not be able to observe changes at the molecular level in order to explain the changes that take place. The simulation has been designed to assist you in generating mental models to understand abstract concepts better. The simulation will be integrated with the regular class lecture, labs and exercises. To facilitate the learning you will be assigned a project that you will work on in-groups. I will be interviewing your group at three different stages of the project. The questions generated during the interview will help you in generating a model of the chemical equilibrium that you will evaluate and modify as progress is made from one stage to another. The conversation that will take place during the interviews will be audio-recorded so that the interviews can be evaluated to identify any
121 alternate conceptions that may occur while learning Le Chatelier’s Principle. This study will take place over three weeks, May 23-June 13, 2005. Your permission is being sought concerning the audio recording during class. Participants will not be asked to do anything different or unusual in the lesson or in the way that they work. At the completion of the project, I will be very happy to play the audiotapes to the participants if they wish and the only people who will listen to the audiotapes apart from them will be the project investigators. No one else will listen to the tapes. You will of course be free to opt out of the project at any time and such withdrawal will not affect your grades or relationship with the school in any way. Apart from being videotaped, participants will not be treated in any way differently from non-participants who will be doing the same work, as they will be. The audiotaping will not affect the teaching of the normal lesson. The equilibrium project and the interviews are a normal part of the instruction. Students who do not consent to audio recording will have their voices erased when the data is accessed. This procedure will be carried out only after the course is completed and students have been assigned their final grades. With the volunteer teacher’s help, students who do not consent to audio recording will identify their voices and the volunteer teacher will delete their voices from the recordings. The data will only be accessed and analysed after the course is over and grades have been assigned. Your permission is also being sought to complete a confidential, anonymous, initial assessment about scientific concepts that will be administered during normal classroom time. Confidentiality will be preserved on the initial assessment with the use of false numerical identifiers instead of names of student participants and their schools. Students will have the option of being identified by name instead of numerical identifier on the initial assessment if they so wish and with their parents’ approval.
Participation and Confidentiality: Any information resulting from this study will be kept strictly confidential. All data will be kept in a locked cabinet in the Science Prep Room. Any report that is written concerning this study will, by giving false numerical identifiers, preserve the complete anonymity of all participants and their schools, unless a participant would like to be identified by name. At the end of the project, I may ask students whether I may use parts of the audiotapes at conferences such as the Catalyst Conference. Your parents will be contacted at this later stage to give your permission. You do not have to make that decision until you have listened to the tapes. Contact: If you have any concerns about your rights or treatment as a human subject, you may contact the Research Subject Information Line in the University of British Columbia Office of Research Services at 604-822-8598. If you have any other questions please contact me School.
Consent: Please understand that participation in this project is entirely voluntary and that you may refuse to participate or withdraw from the project at any time without jeopardy to your class standing, grades, or relationship with the school. Please complete the attached Consent Form to indicate whether you do or do not give your consent to participate in the classroom study. Keep this description of the study for your own reference and detach the consent slip below. You will be submitting the consent slips to the volunteer teacher.
122 Thank you.
Sharmila Pillay Chemistry Teacher MA student in the Faculty of Education, UBC.
123 DETACH CONSENT SLIP AND RETURN TO VOLUNTEER TEACHER
STUDENT CONSENT FORM Consent for classroom observations, audio recording, and initial assessment.
Please check the box indicating your decision:
I CONSENT to participating in the study as described in the above form.
I DO NOT CONSENT to participating in the project as described in the form.
I acknowledge that I have received a copy of this consent form.
Date: Student name Div: Student Signature
124 Appendix D: TEMBS Research Plan 2005
The following is the plan for the research study that will be carried out with two classes of Chemistry 12 students in May-June 2005. The study will be on unit 2, Chemical Equilibrium, and will take place over three weeks. Please see notes below the table for a description of each item on the following table.
Class A and Class B Equilibrium Primer Equilibrium Pretest Introduce Equilibrium group Project (Please see ‘Equilibrium Model Project Outline’, for details on this project.)
Class A Class B Traditional Simulation (Lecture, Labs, Demos, etc)
Equilibrium Mid-Test Equilibrium Mid-Test Equilibrium Survey #1 Equilibrium Survey # 1 Equilibrium Interview #1 Equilibrium Interview #1
Class A Class B Simulation Traditional
Equilibrium Interview #2 Equilibrium Interview #2 Equilibrium Post-Test Equilibrium Post-Test Equilibrium Survey #2 Equilibrium Survey #2 Presentation of Presentation of Equilibrium Project Equilibrium Project
Notes: 1. Primer: This is the introduction of the unit. Students will: A. Look at potential energy diagrams B. Determine entropy and enthalpy changes from a chemical equation (qualitatively). C. State that a system will tend toward a position of minimum enthalpy and maximum entropy
125 D. Predict the results when enthalpy and entropy factors favour products, favour reactants or oppose each other.
2. Pre-Test – The pre-test intends to identify the distribution of students in terms of ability. It will also serve as a standard in order to compare the other tests with. Its comparison with the mid-test for both the classes will indicate which method of instruction had a greater effect on improving student understanding.
3. Model Phase 1 – This is the first phase of the Model Project. The students will show their initial understanding of the concept of chemical equilibrium by constructing a model, e.g. a drawing of how they see a chemical equilibrium. These will be collected and will provide a basis for the interview questions.
4. Interview # 1 – This interview will take place between the teacher and the student based on the Equilibrium Project students are working on. The conversation will be audio- recorded. Please see “Interview Questions” for a list of sample interview questions. The questions will be dependent on how the conversation takes place so there is no particular format or order of the questions.
5. Traditional Method – This includes lecture, discussion, labs, and demonstrations. This is the normal process of instruction. Simulations are not part of this method.
6. Simulation – The simulation will be used over the same number of days as the traditional method. At the end of both the traditional classes and the simulation classes, students will write the mid-test.
7. Mid-Test- the mid-test will compare as to which method of instruction is more effective than the other in terms of improving student performance by comparing the results to the pre-tests.
8. Survey #1 – Students will complete a set of questions at the end of this section (please see Survey Questions)
9. Model Phase 2 – Students will represent their understanding after having completed both methods of instruction, traditional and simulation. The models presented here will show if there is any difference in construction of models if the sequence of instruction is changed. Students will be presenting their final work in the form of a poster or on the computer.
10. Interview # 2 – Final interview based on a review of the 3 models and how they have evolved.
126 11. Post-test – The post-test will compare which sequence of instruction is the most effective by comparing the post-test score between the two classes. 12. Survey # 2 – At this stage students have completed the entire sequence of instruction and they will complete a survey which will suggest according to the students, their understanding of the concept of Le Chatelier’s Principle and Chemical Equilibrium.
127 Appendix E: Equilibrium Project Outline
Chemical Equilibrium Project
TASK:
Design and construct a DIAGRAM representation of a chemical equilibrium system.
PROCEDURE: 1. In groups of three or four, brainstorm ideas on how you would represent the following: A. A reaction (choose one) starting with either reactants or products (Stage 1) B. The same reaction showing how the rate of forward reaction, rate of reverse reaction, concentration of reactants, and concentration of products change over time shown in a series of stages until it reaches equilibrium. C. Now apply a stress (e.g., increase temperature) to the equilibrium and again show a series of stages the reaction will undergo in order to reach equilibrium. D. Apply another stress (e.g. change in pressure) and continue in the same way until equilibrium is re-established.
2. Draw and write down some of your ideas and discuss with me before proceeding with the project.
3. You will be interviewed at 2 different stages of the project (Start of project, and at the completion of the project. Please remember to write down your developments in this project as you proceed through the project.
4. Present the project as a poster or some other way of representing your idea at the end of the project (e.g. on the computer, etc)
Time Length for the Project:
One week
You will get 20-25 minutes from 4 classes and the rest of the Project will be done during tutorials after school).
Assessment:
This Project will be worth 10% of the overall class mark.
128 Appendix Fi: Equilibrium Pre-test
Pretest
Student ID ______
Part A – Multiple Choice Put all answers in the blanks 1____ 2 ____ 3 ____ 4 ____ 5 ____
1. Equilibrium is reached in all reversible chemical reactions when the: A. Rates of the opposing reactions become equal. B. Forward reaction stops. C. Reverse reaction stops. D. Concentrations of the reactants and the products become equal.
2. Consider the following reaction:
Heat + CH4 (g) + 2H2S(g) <---> CS2(g) + 4H2(g)
Considering enthalpy and entropy changes, the reactants, if left alone will: A. Not react due to the change in entropy. B. Not react at all. C. Reacts completely to form products. D. Reach a state of equilibrium with the products.
3. Which statement most accurately describes the following chemical reaction?
3C(s) + 3H2(g) ---> C3H6(g) ΔH = +20.4 kJ
A. The progress of the reaction cannot be determined from this information. B. The reaction will proceed to completion. C. The reaction will not proceed at all. D. The reaction will reach a state of equilibrium.
4. For the forward reaction:
CaCO3(s) + 2HCl(aq) <---> CaCl2(aq) + CO2(g) + H2O(l) + heat
A. Entropy and enthalpy both decrease. B. Entropy increases and enthalpy decreases. C. Entropy decreases and enthalpy increase. D. Entropy and enthalpy both increase.
5. When solid KI dissolves in water, heat is absorbed. This process may be described as:
129 A. Endothermic, resulting in an entropy decrease. B. Exothermic, resulting in an entropy increase. C. Exothermic, resulting in an entropy decrease. D. Endothermic, resulting in an entropy increase.
Part B – Written
1. What are the four characteristics of all chemical equilibrium systems? (2 marks) a)______b)______c)______d)______
2. Consider the following exothermic reaction:
C3H8(g) + 5O2(g) --> 3CO2(g) + 4H2O(g) + heat a) Will the above reaction reach equilibrium? Yes or No. (1 mark) ______b) Explain in terms of increasing or decreasing entropy and enthalpy. (2 marks)
______
3. Chemical reactions tend toward a position of minimum enthalpy and maximum entropy.
A) What is meant by the term enthalpy? (1 mark) ______
B) What is meant by the term entropy? (1 mark) ______
130
4. i) Describe the nature of dynamic equilibrium. (2 marks)
______ii) Draw a model (diagram) of a reaction before it reaches dynamic equilibrium and after it reaches dynamic equilibrium. (Use dots, stars, etc to represent molecules and arrows to show direction of the reaction). (2 mark)
Before:
After:
131
5. Describe how enthalpy and entropy change in the forward direction as an exothermic reaction reaches equilibrium. Explain. (3 marks)
Enthalpy: ______Entropy: ______Explanation: ______
132 Appendix Fii: Equilibrium Mid-Test
Mid Test Student ID ______
There are 5 multiple-choice questions and 5 written questions.
Part A: Multiple Choice Please write your answers in the space provided at the end of the Multiple Choice section. 1. Temperature is gradually decreased then held constant in an exothermic equilibrium. Which of the following represents the change in the reverse reaction rate?
A. B.
reverse reverse reaction reaction rate rate
time time
C. D.
reverse reverse reaction reaction rate rate
time time
2. Consider the following equilibrium: 2+ - 2- Cu (aq) + 4Br (aq) + Heat ⇔ CuBr4 (aq) Blue colourless green
Which of the following will cause this equilibrium to change from blue to green?
A. adding NaBr(s) B. adding NaNO3(s) C. adding a catalyst D. decreasing the temperature Use the following equilibrium equation to answer questions 3 and 4.
CO2(g) + H2(g) ⇔ H2O(g) + CO(g)
133 3. Which two stresses will each cause the equilibrium to shift to the left?
A. increase [H2], increase [CO] B. decrease [H2], increase [H2O] C. increase [CO2], decrease [CO] D. decrease [CO2], decrease [H2O]
4. Which of the following graphs represents the forward rate of reaction when H2O(g) is added to the above equilibrium at time = t1 ?
A. B.
rate rate
t1 time t1 time C. D.
rate rate
t1 time t1 time
Answers: 1. _____ 2. _____ 3. _____ 4. ______
Part B: Written 5. Consider the following equilibrium:
2NF2(g) ⇔ N2F4(g) a) Equilibrium shifts to the right when volume is decreased. Describe the changes in reaction rates that cause this shift to the right. (2 marks) ______
134 b) i) Draw a diagram (graph) to represent what you may see at the molecular level initially when the volume is decreased. (2 marks)
ii) Draw a diagram (graph) describing what happens to the system, as equilibrium is re-established. (2 marks)
6. Methanol, CH3OH, is produced industrially by the following reaction:
CO(g) + 2H2(g) ⇔ CH3OH(g) + heat a) State two different methods that would cause the equilibrium to shift to the right. (2 marks) i)______
______
ii)______
______
b) In terms of rates, explain why these methods cause the equilibrium to shift to the right. (1mark) ______
135 7. Consider the following equilibrium and accompanying graph: 2+ - Zn(IO3) 2(s) ⇔ Zn (aq) + 2IO3 (aq)
- [IO3 ]
[Ions]
[Zn2+]
t1 t2 t3 a) Identify the stress applied at t1. (1 mark)
- b) Complete the above graph from t1 to t3 for the [IO3 ]. (2 mark)
c) Explain what happens at the molecular level:
from t1 to t2 ______
from t2 to t3 ______
8. Consider the observations for the following equilibrium:
N2O4(g) ⇔ 2NO2(g) (colorless) (brown)
136 Trial Temperature°C Colour I. 10 Light brown II. 50 dark brown
a) Sketch the potential energy curve on the graph below for this equilibrium. (1 mark)
PE
progress of the reaction
b) Explain the colour change using Le Chatelier’s Principle. (1 mark) ______
c) Other than changing the temperature, what other changes could be done to cause a shift to the left? (1 mark) ______
9. Consider the following reaction:
3+ - 2+ Fe (aq) + SCN (aq) ⇔ FeSCN (aq) yellow colourless red
When a few drops of 6.0 M NaOH is added to 25.0 mL of the above system, a precipitate of
Fe(OH)3 forms and the solution turns pale yellow. a) Explain this colour change in terms of Le Chatelier’s Principle. (2 marks) ______
137 b) Describe the effect on the rate of the reverse reaction as the colour change occurs. (1 mark) ______
138 Appendix Fiii: Equilibrium Post-test
Post Test Student ID: ______
There are 5 multiple-choice questions and 5 written questions.
Part A: Multiple Choice Please put answers to multiple-choice questions in the space provided at the back.
Use the following equilibrium to answer questions 1 and 2.
N2O4(g) ⇔ 2NO2(g) colorless brown
1. If N2O4 is placed in a flask at a constant temperature, which of the following is true as the system approaches equilibrium?
A. The color gets darker as [NO2] increases. B. The color gets lighter as [NO2] decreases. C. The color gets darker as [N2O4] increases. D. The color gets lighter as [N2O4] decreases.
2. The system above reaches equilibrium. Considering enthalpy and entropy factors, which of the following is true with respect to the forward reaction?
A. The entropy is increasing and the reaction is exothermic. B. The entropy is decreasing and the reaction is exothermic. C. The entropy is increasing and the reaction is endothermic. D. The entropy is decreasing and the reaction is endothermic.
139 3. Consider the following equilibrium:
CaCO3(s) ⇔ CaO(s) + CO2(g) ΔH = +175kJ
Which of the following diagrams best represents the change in the concentration of CO2 as temperature is decreased at time t1?
A. B.
[CO2] [CO2]
t1 t1 Time Time
C. D.
[CO2] [CO2]
t1 t1 Time Time
4. Limestone is decomposed to make quicklime (CaO) according to the following equilibrium:
CaCO3(s) + 175kJ ⇔ CaO(s) + CO2(g)
Which of the following conditions would produce the greatest yield of CaO(s)?
Temperature Pressure A. Low Low B. Low High C. High Low D. High High
5. Some Fe3+ and SCN- were mixed and established the following equilibrium:
140
3+ - 2+ Fe (aq) + SCN (aq) ⇔ FeSCN (aq)
What happened to the reverse rate and [Fe3+] as equilibrium was established?
A. The reverse rate decreased and [Fe3+] increased. B. The reverse rate increased and [Fe3+] increased. C. The reverse rate decreased and [Fe3+] decreased. D. The reverse rate increased and [Fe3+] decreased.
Multiple Choice answers: 1. _____ 2. _____ 3. _____ 4. _____ 5. ______
Part B: Written 6. Consider the following equilibrium: + + Al(H2O)4(OH)2 (aq) ⇔ Al(H2O)3(OH)3(s) + H (aq)
a) Some HCl(aq) is added to the equilibrium. What happens to the amount of solid Al(H2O)3(OH)3? Explain. (2 marks) ______
b) The HCl is added at time t1 and equilibrium is re-established at time t2. On the axis below, sketch what happens to the reverse reaction rate. (2 marks)
Reverse Reaction Rate
t1 t2 Time
7. Consider the following equilibrium system:
C(s) + 2H2(g) ⇔ CH4(g) ΔH = -75kJ
State three different ways to make more C(s) react. (3 marks) i) ______ii) ______iii) ______
141 8. Consider the following graph for the reaction: H2(g) + I2(g) ⇔ 2HI(g)
1.0 (0.8)HI 0.8 Concentration (0.6)H2 (mol/L) 0.6
0.4 (0.2)I2 0.2
0 t1 t2 t3 Time
The temperature is increased at t1 and equilibrium is re-established at t2. a) On the graph, sketch the line representing the [HI] between time t1 and t2. (1 mark)
b) Calculate Keq at time t2 – t3 (2 marks)
c) Generate molecular level models (Use some form of representation such as dots, stars, etc) to show what is happening in the situation above from t1-t3. i)Your models must show how molecules of HI, H2, and I2 will change in concentration. (1 mark each) ii) Provide a possible explanation for each model below the diagram. (1 mark each).
i) At t1
142 ii) Time t1 – t2
iii) Time t2 – t3
9. Consider the following reaction for the Haber process for ammonia production:
N2(g) + 3H2(g) ⇔ 2NH3(g) ΔH = -92 kJ
The system is normally maintained at a temperature of approximately 500°C. a) Explain why 1000°C is not used. (1 mark)
b) Explain why 100°C is not used. (1 mark)
143 Appendix Gi: Interview Consent
April 24, 2005
Principal Investigator: Dr. S. Khan, Faculty of Education, Department of Curriculum Studies, University of British Columbia. Telephone: 822-5296. e-mail: [email protected]
Introduction:
I am inviting you to participate in the interview aspect of an action research project entitled “Using Simulations in Chemistry 12 to generate model-based learning of abstract concepts such as Le Chatelier’s principle”. The principal investigator is a researcher from the University of British Columbia. As an action research project, you will be able to help generate research questions and guide the research in ways that are important to your learning.
Purpose:
The purpose of this study is to explore student understanding of unobservable phenomena in science and consider the ways in which understanding can be fostered with the use of new media technologies in the classroom. I am inviting you to participate in this study because the simulation that will be used in this study is based on Le Chatelier’s principle and its application in the chemical equilibrium unit. This unit is an important part of the course content in the chemistry 12 curriculum as it contributes towards the understanding of solubility equilibrium and acid base equilibrium. As part of this study, you will be working on a project on chemical equilibrium. While engaging in this project with your group members, you will evolve an understanding of chemical equilibrium, and Le Chatelier’s principle through model based learning.
Study Procedures:
You have been invited to take part in the interviews that will take place at three different stages of the Equilibrium project (Please see attached outline of this project –Appendix E). The project will take place over one week and you will get class time to work on this project. The first interview will take place after an introduction to the project and this will highlight your initial ideas of your project. The second phase of the interview will address further questions and suggestions regarding the progress made in the project. Finally, the third phase of the project will address questions related to conclusion of the project. The interview questions during the three stages are designed to
144 assist you in the development of your project. The interviews will be audio recorded. During these sessions you are invited to bring your own questions and concerns related to the project that will help to further evaluate and modify your work. You will be presenting your project to the class on the completion of the project.
Anonymity and Confidentiality:
Any information resulting from the interview aspects of the research study will be kept confidential and your individual identity will be kept strictly anonymous. In addition, any information resulting from this study will be kept strictly confidential. Furthermore, only researchers will have access to the data and all tapes will be kept in locked filing cabinets. The researchers will be using all forms of data in presentations, publications and media. As a research participant, you have the right to access all original data transcripts upon request. There are no known risks to participating in this study.
Contact:
If you have any concerns about your treatment or rights as a research subject you may contact the Research Subject Information Line in the University of British Columbia Office of Research Services at (604) 822-8598.
If you have any questions or desire further information with respect to this study (including questions about the procedures used) you may contact me directly at school.
Consent:
Students: I will be expected to engage in all class activities, which are also the research activities. I understand that my participation in this research will not affect my grade in any way. To insure this, when I am done with this form, I will submit this to the volunteer teacher who will place this form along with the forms from all the other students in a secure filing cabinet only accessible to the volunteer teacher. The locked cabinet will not be opened until after the grades have been posted. At the time when the grades are posted, the researcher will still have no idea whether I have opted to participate in the research or not until two weeks later. This allows me to change my mind after having engaged in all of the class/research experiences to see if I want my data to be used in the research.
I understand that my participation in this study is entirely voluntary and that I may refuse to participate or withdraw from the study at any time. My participation level will not affect me negatively in any way.
I consent to participate in the interviews.
145
______Participant Signature Date
______Parent Signature Date
146 Appendix Gii: Interview Questions
1.) Describe the procedure/method your group used to initiate this model. -Who contributed what ideas? -Were there any disagreements and why?
2.) Why did you choose this form of representation? [Generate]
3.) How did you create this model?
4.) Explain what your model is representing. [Evaluate]
5.) What changes are you planning to make with your model? [Modify]
*Please note these are the main questions that would facilitate the interview but there will be some spontaneous questions that may arise as a result of the conversation between the students and the teacher. *Please note that this is the first interview based on Model Phase 1. Questions will be added to this interview on the second interview. Examples: a) What changes were made as you developed the model and why? (Students will have their original models to compare with)
147 Appendix Hi: Student Survey Consent
April 24, 2005
I am inviting you to participate in a research project entitled “Using Simulations in Chemistry 12 to generate model-based learning of abstract concepts such as Le Chatelier’s principle”. The principal investigator is a researcher from the University of British Columbia. I would like for you to be involved in the research by completing this attached survey.
The purpose of this study is to explore student understanding of unobservable phenomena in science and consider the ways in which understanding can be fostered with the use of new media technologies in the classroom. I am inviting you to participate in this study because the simulation that will be used in this study is based on Le Chatelier’s principle and its application in the chemical equilibrium unit. This unit is an important part of the course content in the chemistry 12 curriculum as it contributes towards the understanding of solubility equilibrium and acid base equilibrium. Some of the themes of this survey include: the role of simulations in the chemistry 12 curriculum, the effectiveness of other forms of instructions such as lecture and labs, and the different ways students learn chemistry.
For your information, the survey will take approximately 15-20 minutes. Any information resulting from this survey will be kept strictly confidential and your identity will be kept completely anonymous. You will not be required to use your names on the survey. Furthermore, only researchers will have access to the data and all data will be kept in locked filing cabinets. As a research participant, you have the right to access all data transcriptions upon request. You may refuse to participate or withdraw from the study at any time. Your participation or lack thereof will in no way affect your grade or class standing. There are no known risks to participating in this study.
If you have any concerns about your treatment or rights as a research subject you may contact the Research Subject Information Line in the University of British Columbia Office of Research Services at (604) 822-8598.
If you have any questions or desire further information with respect to this study (including questions about the procedures used) you may contact me directly at the school.
148 It will be assumed that you have given your consent to participate in this survey if you proceed to fill it out.
Sincerely yours
______Sharmila Pillay Chemistry teacher MA student in the Faculty of Education, UBC.
Dr. Samia Khan Principal Investigator
149 Appendix Hii: Survey #1
Please respond to the statements using the A to E legend below. A= strongly agree B= generally agree C= neutral or agree and disagree about the same D= generally disagree E= strongly disagree
1.) I am more of a visual learner than an auditory one. 2.) I am not anxious about using computers in science. 3.) Demonstrations of chemical phenomena are more effective for my learning than an interactive simulation of the same chemical phenomena. 4.) Chemistry is one of the more interesting sciences. 5.) Chemistry is too abstract to understand deeply. 6.) Teaching chemistry to others would help me understand the concepts better. 7.) I am anxious about learning chemistry. 8.) I have created a model (such as a representation of a molecule or cell) in science before. 9.) I believe educational computer programs can help me learn. 10.) I have seen simulations (computer animations that can interact with the user and provide feedback) in a science class before. 11.) I am confident about my ability to solve chemistry problems. 12.) There are more frequent opportunities to generate scientific ideas in this class than in most other classes. 13.) Peer discussion is valuable for my understanding of science topics. 14.) I was frequently asked to analyze scientific data from a graph or table in previous science courses. 15.) Reading and reviewing problems in a textbook is usually where I learn how to solve problems in chemistry. 16.) I modify my ideas about chemistry more often because of classroom discussion then from doing homework. 17.) By the conclusion of class, I usually feel I understand the chemistry concept of that lesson. 18.) I believe that student participation in the class will contribute to my understanding of chemistry. 19.) I believe computer simulations will contribute to my understanding of chemistry. 20.) I believe tutorials will contribute to my understanding of chemistry. 21.) Labs contribute to my understanding of chemistry. 22.) I do not benefit from the questions and discussions in class. 23.) I do not find the notes and lecture in class useful.
150 Appendix Hiii: Survey #2
Section 1 Please respond to the statements using the A to E legend below. A= strongly agree B= generally agree C= neutral or agree and disagree about the same D= generally disagree E= strongly disagree
1.) Demonstrations of chemical phenomena are more effective for my learning than an interactive simulation to the same chemical phenomena. 2.) I become frustrated if a computer program does not respond according to my expectations. 3.) I believe educational computer programs can help me learn. 4.) I would like to see an animation of molecules in chemistry in order to enhance my learning of the subject. 5.) I am confident about my ability to solve chemistry problems. 6.) There are more frequent opportunities to generate scientific ideas in this class than in most other classes. 7.) An important advantage of the computer simulations is that they make unobservable processes in chemistry more explicit to me. 8.) Qualitative rules or concepts that are descriptive and non-mathematical help me understand chemistry. 9.) Peer discussion is valuable for my understanding of science topics. 10.) Reading and reviewing problems in a textbook is usually where I learn how to solve problems in chemistry. 11.) When using computer simulations in class, if I do not understand the concept before hand, the in-class simulation compounds my confusion instead of clarifying the concept. 12.) I am not anxious about using computers in science. 13.) It is difficult to determine what the important information is in the in-class computer simulations. 14.) It would aid my understanding if the simulations in class were paired with a concrete demonstration or a lab activity wherever possible. 15.) I modify my ideas about chemistry more often because of classroom discussion than from doing homework. 16.) The simulations have contributed to the development of my ability to critically analyze a chemistry problem more than the labs. 17.) Having us generate, evaluate, and modify relationships is valuable to my understanding of the concepts in chemistry. 18.) I have to modify some of the initial relationships I generated in class.
151 19.) An important advantage of the computer simulations is that they make unobservable processes in chemistry more explicit to me. 20.) Teacher guidance is necessary for the effective use of simulations.
For the remaining questions below, please use the scheme below: A= 1st B= 2ND best C= 3rd best D= 4th best E= 5th best F=6th best
Rank where the greatest learning happens for you in chemistry between Q. 1 to 6 from 1 to 6th best. Assign each of the rankings only once between #1-#6.
1.) Classroom demonstrations. 2.) Classroom simulations. 3.) Laboratories. 4.) Peer discussion. 5.) Reading the textbook. 6.) Teacher discussion with students during class.
Section 2
Please write your responses to the following questions in the space provided.
SIMULATION
1. What feature(s) of the simulation did you find the most interesting, and why? ______
2. What benefit(s) will using this simulation have in understanding chemical equilibrium and Le Chatelier’s principle? ______
152 ______
3. How do you think this simulation can be improved to help understand the concept of chemical equilibrium better? ______
EQUILIBRIUM PROJECT
1. What did you like the most while working on this project and why? ______
2. Did your understanding of the concept of chemical equilibrium change while working on this project? If yes, how? ______
3. In what ways did this project improve your understanding of the concept of chemical equilibrium? ______
153 ______
4. How do you think this project could be changed to improve your understanding of chemical equilibrium and Le Chatelier’s principle? ______
154 Appendix Ii: Simulation Activity # 1
Student ID: ______
Instructions: Go to http:www.cs.ubc.ca/~ferstay/tembs/tembs_2005Mar26.zip i) Download Manager ii) Double click on tembs_2005Mar2 iii) Click on ‘Reveal in Finder’ iv) Double click on tembs_2005Mar26 2 v) Double click on tembs_2005Mar26_1375.jar vi) Wait for a few seconds
1. For the following reaction:
PCl5 ⇔ PCl3 + Cl2
a) Draw this system at equilibrium using molecules and explain your drawing (Use different colors to represent the molecules and include a legend). Draw the molecules at time t1 and t2 to illustrate the equilibrium.
t1
t2
155
b) i) Predict what would happen to the concentration of Cl2 and PCl3 if the concentration of PCl5 were increased? Draw the system to show changes in the equilibrium that would take place in the following situations:
Initially (When PCl5 is added)
Changes in the concentration of Cl2, PCl3, and PCl5.
c) Generate a “rule” regarding concentration and its effect on a chemical reaction at equilibrium.
d) Now go to the simulation on your computer. Run the simulation for 30 seconds approximately and evaluate the relationship you constructed in c). You can increase the concentration of PCl5 by moving the PCl5 slider. Click on ‘Start’ under the molecular screen. Look at the graphs and the molecular view and modify your initial rule if necessary below. Explain what you have changed and why.
156
2. a) Without resetting or running the simulation, predict what would happen to the concentrations of PCl5 and PCl3 if the concentration of Cl2 were increased. How would the graph and molecular system change?
b) Without resetting or running the simulation, predict what would happen after three days if no changes were made to the system after Cl2 had been increased. Would the graph and molecular view look different from a) above? If so, how?
c) Using the simulation, generate a rule about the effect of changing the concentration on the products.
d) Using the simulation, evaluate your rule and your predictions. What do you observe? Modify your rule if necessary.
3. Go to ‘Edit’ and select the Prediction Mode. Click on start on the molecular view screen. Wait for a few seconds. Answer the prediction question when it appears on the screen by clicking on A,
157 B, C, or D. Then click on ‘Predict’ under the molecular view screen to check your answer. Answer the first question on this worksheet before continuing.
Q: What happens to the concentration of PCl3 if the number of moles of PCl5 changes to 30.0? Your answer: ______Explain your answer: ______
Correct answer: ______Now click on ‘Continue’ and observe the changes on the graph. Wait for the next question. Answer the rest of the questions that will appear (Wait for a few seconds).
4. a) Predict what is the effect of volume on the concentrations of the reactants and products in the above chemical reaction. Increasing Volume:
Decreasing Volume:
b) Now using the simulation evaluate the relationship you constructed in a). You can increase the volume of the reaction by moving the volume slider. Click on ‘start’. Look at the graphs and the molecular view and modify your prediction if necessary below. What changes do you observe and explain why.
158
b) Generate a rule about volume and its effects on a chemical reaction.
5. Go to ‘View’ and select Analogy. Also select the ‘Prediction Mode’ under ‘Edit’. Click on start on the analogy view screen. Answer the prediction question when it appears on the screen:
What happens to the concentration of PCl3 if the number of moles of PCl5 changes to 30.0? i) Select your answer by clicking on A, B, C, or D on the graph and click on predict on the analogy view. ii) Click on ‘continue’ and observe the analogy view as well as the graphs.
a) Describe what happens to the concentrations of Cl2, PCl3, and PCl5 ______b) Explain the above results ______c) Give two important properties of chemical equilibrium illustrated by the analogy view? ______d) Generate an analogy that you could use to explain how a system reaches equilibrium. Use diagrams and explanations.
159 Now switch back to Molecular View and cancel ‘prediction mode’ before proceeding with the next question. 6. Temperature i) Decrease the temperature to about 31 K. Click ‘start’. What happens to the concentrations of:
a) PCl5 ______
b) PCl3 ______
c) Cl2
ii) What type of reaction is the forward reaction (Endothermic or Exothermic)
iii) Explain your answer to the question above.
______
160 Appendix Ji: Pilot Study Pre-test
1. Consider the following equilibrium system: + - NH3 (aq) + H2O (l) ⇔ NH4 (aq) + OH (aq) Which of the following when added to the above equilibrium system, would cause an increase in [OH-] ?
A. NH3 B. H2O + C. NH4 D. OH-
2. Consider the following equilibrium system: N2 (g) + 3H2 (g) ⇔ 2NH3 (g) + 92 kJ Which of the following sets of conditions will favour the formation of the product? A. low pressure and low temperature B. low pressure and high temperature C. high pressure and low temperature D. high pressure and high temperature
3. Consider the following equilibrium: N2 (g) + 3H2 (g) ⇔ 2NH3 (g) + 92 kJ In which of the following will both changes shift the equilibrium right? A. An increase in volume and a decrease in temperature. B. An increase in volume and an increase in temperature. C. A decrease in volume and a decrease in temperature. D. A decrease in volume and an increase in temperature.
4. Consider the following equilibrium: 2HI(g) ⇔ H2 (g) + I2 (g)
At constant temperature and volume, more I2 is added to the above equilibrium. A new state of equilibrium results from a shift to the
A. left with a net decrease in [H2]. B. left with a net increase in [H2]. C. right with a net increase in [H2]. D. right with a net decrease in [H2].
5. Consider the following equilibrium: 2SO3 (g) ⇔ 2SO2 (g) + O2 (g)
At equilibrium, the rate of decomposition of SO3 A. equals the rate of formation of O2 B. equals the rate of formation of SO3 C. is less than the rate of formation of O2
161 D. is less than the rate of formation of SO3
6. Consider the following equilibrium: 2HI(g) ⇔ H2 (g) + I2 (g) ΔH= -68 kJ Which of the following would cause the equilibrium to shift right? A. Increasing the volume. B. Decreasing the volume. C. Increasing the temperature. D. Decreasing the temperature.
7. Consider the following equilibrium: PCl5 (g) ⇔ PCl3 (g) + Cl2 (g)
The equilibrium concentration of PCl5 will increase when A. PCl3 is added. B. Cl2 is removed. C. a catalyst is added. D. the volume of the container is increased.
8. Consider the following equilibrium: N2O4 (g) + 58 kJ ⇔ 2NO2 (g) The equilibrium shifts right when
A. NO2 is added. B. N2O4 is removed. C. the temperature is decreased. D. the volume of the system is increased.
9. Consider the following equilibrium: PCl3 (g) + Cl2 (g) ⇔ PCl5 (g) ΔH= -88 kJ
What happens to the [PCl3] when additional Cl2 is added at constant temperature and volume? Explain. ______(2 marks)
10. Consider the following equilibrium: 2 NO(g) + Cl2 (g) ⇔ 2 NOCl(g) ΔH= -77 kJ
What happens to the amount of Cl2 when the following changes are imposed? Explain, using Le Chatelier’s principle. a) Removing NO(g). (1 mark)
162 ______b) Decreasing the temperature. (1 mark)
______
163 Appendix Jii: Pilot-Study Post-Test
1. Methanol, CH3OH, can be manufactured using the following equilibrium:
CO(g) + 2H2 (g) → CH3OH(g) + energy
The equilibrium will shift to the right when A. a catalyst is added. B. the [CO] is increased.
C. the [CH3OH] is increased. D. the temperature is increased.
2. Consider the equilibrium:
N2 (g) + 2O2 (g) → 2NO2 (g)
When the volume of the system is increased, how does the equilibrium shift and [NO2] change?
direction of shift [NO2] A. left increases B. left decreases C. right increases D. right decreases
3. Consider the following equilibrium system: CaCO3 (s) → CaO(s) + CO2 (g) Which one of the following changes would cause the above system to shift left? A. Add more CaO.
B. Remove CaCO3. C. Decrease volume. D. Increase surface area of CaO.
4. Consider the following equilibrium system: FeO(s) + H2 (g) → Fe(s) + H2O(g) Which one of the following statements describes the effect that a decrease in volume would have on the position of equilibrium and the [H2] in the above system? A. No shift, [H2] increases. B. Shift right, [H2] increases. C. Shift right, [H2] decreases. D. No shift, [H2] remains constant.
5. Equilibrium is said to be dynamic because the
164 A. forward and reverse reactions stop. B. reverse reaction goes to completion. C. forward reaction goes to completion. D. forward and reverse reactions continue.
6. Which of the following reactions will shift left when pressure is increased and when temperature is decreased? A. N2 (g) + 2O2 (g) + heat → 2NO2 (g) B. N2 (g) + 3H2 (g) → 2NH3 (g) + heat C. CH4 (g) + H2O(g)+ heat → CO(g) + 3H2 (g) D. CS2 (g)+ 4H2 (g) → CH4 (g)+ 2H2S(g)+heat
7. Consider the following equilibrium system: CO2 (g) + H2 (g) → CO(g) + H2O(g) Which of the following, when added to the system above, would result in a net decrease in [H2O] ?
A. CO2 B. H2 C. CO
D. H2O
8. Consider the following equilibrium: Cl2O7 (g) + 8H2 (g) → 2HCl(g) + 7H2O(g) Which of the following would increase the number of moles of HCl ?
A. increase [H2O] B. increase [Cl2O7] C. increase total pressure D. increase volume of the system
9. Consider the following equilibrium system:
3+ - 2+ Fe (aq) + SCN (aq) → FeSCN (aq) yellow Colourless Red
In an experiment, a student places the above equilibrium system into a cold-water bath and notes that the intensity of the red colour increases. The student then concludes that the equilibrium is exothermic. a) Do you agree or disagree? (2 marks) b) Explain ______
165 ______
10. The production of ammonia by the Haber process involves the following equilibrium:
N2 (g) + 3 H2 (g) → 2 NH3 (g) + heat
The table below indicates the percentage of ammonia in equilibrium mixtures at various temperatures. a) Explain why the lower temperature results in a higher percentage of ammonia in the equilibrium mixture. (1 mark) ______b) Explain why a temperature of 500oC is used in the Haber process rather than a lower temperature. (1 mark) ______
166 Appendix K: Pilot Study Simulation Activity Sheet
Activity # 1 Chemical Equilibrium Chem 12
Davidson Le Chatelier’s Principle
1. Go to http://www.chm.davidson.edu/java/LeChatelier/LeChatelier.html
2. For the following reaction:
C (s) + H2O (g) → H2 (g) + CO (g) a) Write the above equation including the enthalpy of the reaction.
b) What is ΔH of the reaction?
TEMPERATURE
3. Predict what happens to the concentration of the products and the reactants when: a) temperature is increased:
______b) temperature is decreased:
c) Move the temperature scroll bar so that the temperature increases and write down what you observe in terms of equilibrium amount(moles) and equilibrium concentration (mol/L) for each of the following? Carbon ______
Water
167
Hydrogen
Carbon Monoxide
d) Why does carbon only show change in amount (moles) ?
PRESSURE: 4. What is the effect of increasing pressure on the following?
Carbon ______
Water ______
Hydrogen ______
Carbon monoxide ______
Explain the above results
CONCENTRATION: 5. What is the effect of adding each of the following to the system? Explain in terms of concentration or amount of other reactants and products.
Carbon ______
168 ______
Water ______
Hydrogen ______
169 Appendix L: Equilibrium Project Photographs
170
171 Appendix M: Glossary
GLOSSARY
GEM: Pattern of teaching that encourages students to Generate (by probing prior knowledge), evaluate (students compare prior knowledge to current knowledge in the classroom) and modify
(reject misconceptions and gain a better understanding of the concept).
MENTAL MODELS: Students’ prior domain knowledge and their perception of the observed phenomenon’s features.
MISCONCEPTIONS: Conceptions that students may build on their own that may differ from the one that the teacher holds or has tried to present.
PRECONCEPTIONS: Ideas or beliefs that students have acquired through their life experiences, formal or informal instruction before instruction in class.
REDOX: Reduction and oxidation reactions.
TRADITIONAL: “Traditional chemistry instruction” refers to lecture, note taking, and labs.
172 Appendix N: UBC Research Ethics Board Approval
173 Appendix O: School District 36 Approval
174