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A Conceptual Understanding of Higher Education Students on Stereochemistry

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A Conceptual Understanding of Higher Education Students on Stereochemistry A CONCEPTUAL UNDERSTANDING OF HIGHER EDUCATION STUDENTS ON STEREOCHEMISTRY Daniele Raupp1, José Cláudio Del Pino1 and Agostinho Serrano2 1Federal University of Rio Grande do Sul, Post Graduate Program in Science Education, Brazil. 2Lutheran University of Brazil, Canoas, Brazil. Abstract: The problems related to the formation of scientific concepts of stereochemistry have been widely discussed in the literature. Some researchers made an argument that the main difficulty in solving those problems resides in the three- dimensional level of visualization. Others, however, argue that the learning problem is related to the fact that the topics in organic chemistry are introduced in a very arid way to students who cannot relate this ‘school science’ with their previous daily experiences. To analyse the conceptual understanding of higher education students on stereochemistry a group of six students received a blank sheet with an open question. After the student answered this question, we conducted interviews under the Think Aloud protocol. By analysing both the written material and the transcripts of the interviews, we noticed that none of the students mentioned any historical fact connected to the theme or to any experiences of their daily lives. There is an appreciation of aspects such as structure, geometry, molecular formula, and nomenclature. This reflects the thinking of Lima et al (2000) who claim "Teaching chemistry often has summarized the mathematical calculations and memorization of formulas and nomenclature of compounds". This understanding of stereochemistry based only on scientific concepts, can be one of the causes of learning difficulties often reported as commented previously corroborated by the aforementioned statement and Gabel (1993) which attributes the difficulties that beginners have to develop a conceptual understanding: Students cannot understand, "phenomena” that are not considered related to the student's everyday life. Keywords: stereochemistry, classroom observation, conceptual understanding, think aloud protocol. BACKGROUND AND FRAMEWORK Concepts of isomerism, molecular geometry, three dimensional structures, asymmetric carbon, absolute configuration, and chirality are addressed not only in disciplines of Organic Chemistry in high school, but as well in higher education. Moreover, in higher education the field of stereochemistry is not only a subject of study in chemistry courses, but also courses in Biology, Pharmacy, and others. The problems related to the formation of scientific concepts in stereochemistry have been widely discussed in the literature, and a consensus has been reached that the main difficulty in solving problems relies in three-dimensional level of visualization required to reason about the phenomena in the molecular level. Difficulty occurs since the ability to visualize three-dimensional aspects of molecules and their relations with other molecules is a considerable challenge (Wu & Shah, 2004; Kozma, Chin, Russel & Marx, 2000). The complexity of problem solving at this level (Baker, George & Harding, 1998) justifies the fact that, for some students, learning stereochemistry can be difficult and sometimes traumatic (Kurbanoglu, Taskesenligil & Sozbilir, 2006). As a result, the weeks spent studying stereochemistry are somehow viewed as frustrating for students (Evans, 1963). Teaching stereochemistry is also a challenge for teachers, as well as to those trying to develop strategies that would facilitate the understanding of scientific concepts, as one must address the overall lack of motivation to study Chemistry itself. The complexity of the issue becomes even more evident when we study the early history of stereochemistry. The challenge of teaching stereochemistry The concept of chemical space (one of the original names of stereochemistry) for some scientists was considered a reverie, being violently criticized. Now, it is deservedly considered a key concept, without which modern chemistry would be almost inconceivable (Ramberg, 2003). The study of the molecule shape has been of such importance to science that it granted the Nobel Prize in Chemistry in 1975 to the two chemists who developed research in the area. The prize was divided equally between John Warcup Cornforth Croatian "for his work on the stereochemistry of enzyme- catalyzed reactions" and Vladimir Prelog "for his research into the stereochemistry of organic molecules and reactions " (Nobel Prize, 2009). But, in the classroom, theses aspects not always are discussed, as Correia et al. (2008) commented, explaining the specific case of Organic Chemistry, the authors claim that it "is introduced so barren for students who cannot relate this school knowledge with previous experience" (2009, p.489). Naturally, seldom the teacher can use as a starting point the so called “everyday knowledge”. It would be startling to relate concepts like conformation, steric hindrance, plane of symmetry and chirality to the spontaneous knowledge of students. In this sense, the lack of student motivation seems to be related to the difficulty in dealing with abstract concepts and not related to their daily lives (Gabel, 1993). According to Lima and colleagues (2000) that "non-contextualization" may be the cause of the high level of rejection of Chemistry that naturally makes the process of teaching and learning somewhat more difficult. The concepts involved in learning stereochemistry are scientific concepts and in order to achieve a cognitive learning of this type of concept cognitive theories demand an action mediated through planned educational activities (Vygotsky, 1993). Santos and Mortimer (1999) discusses that teaching should be contextualized according to the social context considering the economic, social and cultural aspects of the classroom. But differences in approaches aside, it is important to clarify that even employing a contextualized approach to teaching chemistry, there are no guaranties that the classic problems of chemistry teaching will be solved (Chassot, 1993). In other words, relating scientific concepts to everyday phenomena of stereochemistry or even with historicity, does not guarantee success in solving problems teaching in the three-dimensional level. This relationship has the sole purpose of motivating students, since the knowledge that students bring to the classroom come mainly from his interpretation of the macroscopic world. Also, contextualization may help to break some paradigms associated with the level of rejection of learning Chemistry. It is necessary to demystify the image of chemistry as a dogma to avoid the idea of a science basically done by geniuses or something too farfetched (Loguercio et al., 2002). RESEARCH QUESTION So, with the objective of elucidating more the problem of understanding stereochemistry comprehension by students, the research question that guided the data collection was: What is the conceptual understanding of stereochemistry of undergraduating students in Brazil? METHODOLOGICAL FRAMEWORK The methodology used in this work consisted of using two different instruments of data collecting: a) The Blank sheet protocol: sheets were distributed, as well as pencils and pens with different colors among the students. They were asked to write and use any sort of drawing to explain their own concept of Stereoisomerism and b) Think Aloud protocol: interviews focusing on the process used to complete the aforementioned task. Six students participated in the experiment, all of them under graduating in Chemistry, and all of them also who had attended the subjects related to that content at least once previously. The task asked in both instruments was: “Imagine that you are going to explain to another colleague what you know about isomerism. Feel free to write text, equations, formulas, drawings, tables, any way you want.” Upon completion of the tests, we conducted interviews based on technical Think Aloud (Cotton & Gresty, 2006). All interviews were videotaped for later analysis of verbal speech and gestures made during the reporting task execution in the role of representing the different isomers. RESULTS AND DISCUSSION The theme stereochemistry is not a new theme for the students analyzed. In the third year of secondary school the subject is approached, and we took care to choose a sample that had already taken the course Organic Chemistry also in their undergraduation. By analyzing both the written material as the transcripts of the interviews, we noted that none of the students mentioned any historical fact connected to the theme or any such related to their daily lives. There is an appreciation of aspects such as structure, geometry, molecular formula, nomenclature. This reflects the thinking of Lima et al. (2000) who claim that "Teaching chemistry often has summarized the mathematical calculations and memorization of formulas and nomenclature of compounds, without valuing the conceptual aspects." This understanding of stereochemistry based only on pure scientific concepts, can be one of the causes of learning difficulties often reported as commented previously corroborated by the statement and Gabel (1993) which attributes the difficulties that beginners have to develop a conceptual understanding: Students cannot understand, "phenomena” that were not considered related to the student's everyday life. During the interview, as asked how he designed the structure of the but-2-ene, whose molecular formula is C4H8, Student 1 focuses on explaining how to identify the phenomenon checking whether
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