A Foundation to Build: Applying Engineering Principles to Lego Robotics
Stephanie “Spoony” Witherspoon Alexander Hamilton Middle School
Use this material with extreme caution! While in the throes of a Team Challenge event, you may excite, motivate and engage your students into a frenzy of SERIOUS FUN. ~ Lego educational division
INTRODUCTION My degree is in Agriculture Science concentrating on animal science with a specialist degree in Agriculture education from California Polytechnic State University in San Luis Obispo, California. At this point you might be scratching your head with confusion as to why I am writing a curriculum unit for applying engineering principals to Lego robotics. Yeah, I do that too sometimes. It was a series of unfortunate events that led me to this new subject area and a very fortunate future. I went from cows and plows to wires and pliers and could not be happier with the way things have turned out. My unfortunate events (not to bore you with the details) included but were not limited to three major ankle surgeries following a very ungraceful moment on a school farm in Manteca, California, in a turkey house. I found myself back home in Houston, Texas, looking for a position teaching middle school science, not a far stretch from Agriculture Science. I landed a job at Alexander Hamilton Middle School teaching science, and found a school to call home for the past four years. Hamilton is located in the Historic Heights in Houston with a student ethnicity of 15% African American, 73% Hispanic and 12% White. Our students have an attendance rating of 95% with 82% economically disadvantaged students and a drop out rate of .2%. We earned an accountability rating of academically acceptable with the help of 82% of our students passing the reading TAKS test and 92% passing the writing section. Hamilton is more than the percentages that I just mentioned: it is an old building, which just celebrated its 85th anniversary, busting at the seams with new ideas. In this environment teachers are allowed to be individuals, and I have pushed this liberty to its breaking point and have created a new custom-made position. One day while talking to a fellow teacher at Hamilton who dabbled in Lego robotics, I discovered that our school had a couple of Lego robotics kits and that at the moment they were not being used. I borrowed a couple and began playing with robots on the side after school with a handful of students, and we began to have some “serious fun.” That year I chaperoned a small group of students to the TCEA (Texas Computer Educators Association) robotics contest for the other teacher who left our school at the end of that year. I had a blast at the contest, but what amazed me was how hard these students worked at perfecting their robots; they never gave up! I noticed that even while they were frustrated with the difficulty of the task, they never wanted to quit, and they never stopped having fun. At that moment I was hooked and I knew this was what I wanted to teach full time. I fell in love with the subject and realized that I had stumbled upon an outstanding opportunity to excite students about learning.
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I continued using Lego robots in my science classroom and taught an after school program. Finally, I was given an opportunity to teach Lego robotics as an elective one period a year. Lego robotics is a hands-on way to teach problem solving, teamwork, time management, programming, computer skills, physics, and engineering. Now four years later I have been given the opportunity to create a new full-time position to teach this subject to 150 students. I am always looking for ways to expand my program and to increase student learning in my classroom. When this course changed from an after school program taken mostly for fun to an elective course in which we meet regularly, one challenge that I encountered was the need for evaluating student performance. While I want to have a program that makes learning fun, I also want to have a program where students develop usable and marketable skills for their life. Therefore, I decided to participate in the 2005 HTI program to see what new ideas I could develop for my class. In the Lego robotics course I have made a concentrated effort to tie real world applications to the structure of the class by having similar expectations that any engineer would have in a major company, including daily activity reports and adherence to timelines. This year I have also introduced my students to the proper names of the Lego pieces, and I am requiring them to use these names. Instead of students calling the Lego “the small round thing that you put on the ribbed black piece,” I ask the students to say, “I need a full bushing to put on the #3 axel.” Many of the proper names of Lego pieces are common structural material and member names. Two examples of Lego pieces are shown in Figure 1. Figure 1A shows examples of full and half bushings, while Figure 1B shows examples of axels, and Figure 1C shows examples of beams.
Figure 1A Figure 1B Figure 1C If you look at buildings and cars, you will see that some of the key building components are beams, axels, and bushings, and they look very similar to and are used in the same way in the real world as we use them in robotics. I have noted a remarkable improvement in my students’ performance this year in class with the change in structure. There has been a decrease in frustration levels with the improved communication that I directly tie to the use of these proper names of the Lego pieces. I can only imagine how much more improvement and growth my students, and I will experience with the further introduction of engineering terms which are introduced in activity two of lesson one. A conversation with a student just the other day went something like this. “Miss, my robot will not go straight when I have programmed it to go forward on both motors at the same power. I have checked and my robot looks like it is built correctly.” In the past, I would say something like, “Make sure your robot is square, and if it is maybe you should try to change the power on one of your motors to compensate for your design.” Looking at the same situation next year, I imagine my end of the conversation to go more along these lines, “I notice that you have a gripper arm cantilevered off the front right support beam of your robot. Have you considered the impact of the force on the right side of your robot? Maybe you could add some webbing to join the gripper to the left support beam as well, thereby distributing your load more evenly on you robot.” Just imagine the day that I can say that sentence and see full registration of understanding on my student’s face and receive a reply along these lines, “Yes, that is a good idea. I will go and discuss your solution with my team and let you know what we decide to try.” Meanwhile my dean just
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stopped by for a visit and asked for a translation of our conversation. I directed him to the word wall for a little engineering vocabulary crash course. The addition of structural engineering principals to this course will help the students understand the “why” behind unsuccessful attempts to build functional robots and sub- assemblies. “Much of mankind’s development in history, art, science, and economy is intimately intertwined with the fact that some things break while others bend.” While I do not expect my students to become mechanical engineers, I do hope that they will begin to understand that they have control over the quality of their robots, and they can learn to predict if a robot design will be successful because they will have the knowledge of what design qualities make a robot sound in structure. I hope that with the addition of structural engineering concepts, I will see an increase in successful robot design and a decrease in the production of robots that literally fall apart on their way to the challenge table where they are tested. Figure 2 is an example of a very stable and well-constructed robot; this is the Demobot from the Botball contest.
Figure 2 The material from this structural engineering unit will be included in the first six weeks of my Lego robotics class, which is when we cover the “Basics of Robotics.” We also discuss the various Lego pieces and basic structures like the tank robot from the Lego instruction books and off the robotics educator CD which is a structurally sound robot that we use before students start designing and building robots of their own. The material would then be readdressed throughout the school year as needed and appropriated to the topic or challenge that we are covering. Figure 3 shows an example of the first robot that we build in Lego robotics. It is from the Carnegie Mellon Lego Educator CD’s.
Figure 3 UNIT BACKGROUND This unit will last for six to twelve 90-minute class periods depending on how you adapt it to fit your needs. When I started looking at how to add the information from the seminars to my curriculum, I knew exactly what it would look like. It would look like my existing course with an
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emphasis on understanding how structures can be put together to last and with the addition of the vocabulary terms which will give my students the tools that they need to communicate their ideas to each other and to me. After adding the proper names of the Lego pieces to my class in the past year and seeing what a difference such a simple change can make, I am excited to add the terms in lesson one to my course. While it is a large number of terms, I think it is vital to introduce them all early on during the first few weeks of school so that we can use them and master them during the course of the school year. During the past year I found that creating a word wall with pictures of the Lego pieces and their proper names was a big help. With adding such a large amount of information to my course, I will continue the practice of having a word wall that will now include all the Lego pieces and the structural engineering terms. One thing I learned this year is how truly important it is that I lead by example. When I did not know the name to a piece during class, I stopped teaching and went to the word wall to find the proper name, and then once I knew the name, I would continue teaching. It did not take long for my students to catch on and to realize that I was serious, and they knew not using proper Lego names would not be accepted. I know I can achieve the same success this year with these terms if I strive to use them correctly and work them into our daily discussions as often as possible. In lesson two the instruction will move from an introduction of the terms to learning what they mean when you are building a structure. Students will be challenged to build structures to specification, and then that structure will be tested to see if it is stable and to see if it can support a predetermined weight. Students will be encouraged to practice using the new terms when we are discussing the class activities. After testing the structure, they will be asked to present to the class an evaluation of their structures’ performance making sure that they use proper terminology. After having the opportunity to build their own structures, students will build structures using Lego set # 9618 Bridges, Towers, and Other Structures. By using these kits students will have an opportunity to build and test proven structures and will be able to compare what they built on their own to the structures they built following the kit’s instructions. During a teacher-led class discussion, we will work together to discover which traits the most successful structures have in common. This is going to be a critical step in building a strong foundation for the year. If students are able to see what makes a structure sound, then they will be able to build robots that do not fall apart on the way to a challenge. In the final lesson students will first build a tankbot following the instructions from the Carnegie Melon software programs, and then they will be given an introduction to Robolab and how to build a simple program. Once they have built this robot and programmed it, they will be instructed to take the tankbot apart and to build an original robot that can accomplish the same simple program. If this unit is successful, students should be able to build a solid and stable robot that can accomplish this task and then they will be asked to present to the class their robot and describe what attributes made their robot a success. Of course they will be required to use the terms from this unit when appropriate. LESSON PLANS Lesson One: Introduction to structural engineering terms Subject: Robotics Grade Level: 6-8 Objective In this lesson students will be introduced to the many structural engineering terms and will have an understanding of why we want to learn and understand these terms.
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Time Allotment: Two to three 90 minutes class periods Activity One A short class discussion of why we need to learn about structural engineering in order to build better robots. Students will be asked questions and we will fill out the first two sections of a KWL (Know, Want to Know, Learned) chart. Activity Two Students will be given a handout with the following terms and definitions, and we will popcorn read the terms, and I will show examples of each term when possible. Terms 1. Arch – A curved structure that primarily transmits forces through compression reaction. 2. Balance – Equilibrium in movement. 3. Beam –A structural member that supports loads through bending action. 4. Bend – To cause something to change its shape into a curve, by physical force. 5. Bridge – A construction or natural feature that spans a divide. 6. Buttress – A support on the outside of a wall that helps to stabilize a vault or roof. 7. Cantilever – A projecting beam or member supported only on one end. 8. Column – A vertical post divided into a base, a shaft, and a capital at the top. 9. Compression – The stress resulting from a pushing force on a member, which tends to shorten it (the opposite of tension) 10. Compression strength –The maximum compressive force a material can support. 11. Construction – A structure that is put together out of separate pieces of often disparate (unlike) materials. 12. Core – A central and often foundational part usually distinct from the enveloping part by a difference in nature. 13. Cost – The amount or equivalent paid or charged for something. 14. Dead load – The weight of a structure itself, including the weight of fixtures or equipment permanently attached to it. 15. Deflection – A translational deformation. 16. Deform – To alter the shape by stress. 17. Elasticity – The property of recovering original shape and dimensions upon removal of a deforming force. 18. Engineering – The profession of applying scientific principals to the design and construction of buildings and structures. 19. Failure – A state of inability to perform a normal function. 20. Fatigue – The phenomenon leading to fracture under repeated or fluctuating stresses. 21. Flexible – Yielding to influence. 22. Footprint – Plane or space occupied by a piece of equipment. 23. Form – Shape or visible structure of a thing or person. 24. Force – Strength or energy brought to bear. 25. Foundation – The lowest and supporting part of a member or a wall, including the base course. 26. Frame – The structural elements that make up the skeleton of a building or other constructed object. 27. Function – The purpose of something; what something does. 28. Hinge – A jointed or flexible device that allows the pivoting of a structural member. 29. Girder – A large beam of steel, iron, reinforced concrete, or timber used to support concentrated loads at isolated points along its length. 30. Infrastructure – An underlying base or foundation.
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31. Joint – The point where two components of a structure join, but are still able to rotate. 32. Load – A burden; a weight to be carried. 33. Live load – The moving load on a structure, including the weight of people, cars, buildings, and equipment, but not including wind load. 34. Materia l – Matter that may be shaped or manipulated, particularly in making something. 35. Pillar – An upright structure of stone, brick, or metal that holds up part of a building or other structure. 36. Rigidity – The degree of flexibility. 37. Shaft – A long thin object. 38. Shear – The sliding of one layer of material relative to another layer. 39. Span – Distance between the supports of a bridge or arch. 40. Stability – Ability of a system to maintain control when subjected to severe outside disturbances. 41. Strain – Deformation produced on a body by an outside force. 42. Strength – The quality of being strong. 43. Stress – Deforming force per unit area to which a body is subjected. 44. Structure – Name for any complex construction. 45. Stiffness – Rigidity. 46. Suspension – The act of suspending or the state of being suspended. 47. Tensile strength – Breaking strength of a material when subjected to a tensile (stretching) force. 48. Tension – Action of stretching. 49. Test – A session in which a product or piece of equipment is placed under everyday and/or extreme conditions and is examined for its durability, etc. 50. Tie – Attach or fasten. 51. Torque –Force that causes twist in a member. 52. Tower – A structure, usually taller that it is wide. 53. Truss – Structure composed of axial loaded members that intersect at different joints. 54. Web – A connecting element between ribs. Activity Three At the beginning of the activity students will each draw a term and its definition from a container. Students will then be instructed to use the Lego pieces located in their area to construct a visual representation of their term. After approximately 15 minutes each student will present their model to the class and describe how it represents the term. Students will be encouraged to ask questions and offer other ways to represent each term. Activity Four I will put all the terms up on the word wall and we will use the wall together to answer questions and to help in our class discussions. Activity Five Students will fill out the last section of the KWL chart during a teacher led class discussion. Lesson Two: Building a foundation Subject: Robotics Grade Level: 6-8 Objectives In this lesson students will be given an opportunity to apply the terms to the structures they build.
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Time Allotment: Two to four 90-minute class periods Activity One In this activity students will work in small groups, and each group will be given an identical set of Lego building blocks (how many and what types of Lego building blocks depends on availability and teacher preference). Students will be given the challenge to build a tower out of Lego building blocks in which they should try to build the tallest freestanding tower possible. This tower will need to hold a container for a mass or have a place to hook a mass with a hanger. Whichever type of mass you decide to use, it is important that the students see the mass before beginning so that their design takes it into consideration. Once student’s towers are complete, each group should be given the mass to see if their tower can support it. After each group has completed their towers they should compare all the towers during a gallery walk in which each group should collect the following data: tower height, footprint size, widest section, narrowest section, type of core and if it held the mass. After the gallery walk students will discuss each of the towers strong and weak points and try to come to a conclusion as to which towers are the most structurally sound and why. Activity Two In this activity students working in groups of 5-7 will be challenged to build the structures from Lego set # 9618 Bridges, Towers, and Other Structures. After students build each structure, we will come together as a class to discuss what attributes the structure has that make it stable, and if they have ideas to improve the structure and time allows, they can be allowed to try their improvements. Activity Three We will look at pictures of bridges and structures, and together we will practice identifying their structural elements. You can use any books and web pages about bridges and structures for this lesson. I have included a few suggestions in the bibliography. Lesson Three: Testing the foundation Subject: Robotics Grade Level: 6-8 Objectives In this lesson students will get to put what they have learned to the test, and we will see if they have learned enough about structural engineering to be able to build a solid and stable robot that can accomplish a predetermined task and to be able to use the proper terms to describe the outcome. Time Allotment: Two to six 90-minute class periods. Activity One Students will be divided into groups of 5-7 and assigned a Lego robotics team challenge set. After a brief introduction of the kit and an explanation of class procedures for using and storing these materials, students will be asked to follow the instructions on the Carnegie Melon robotics educator CD-Rom for how to build a tankbot. Once the robots are built we will have a brief class discussion about the structure of the tankbot and what elements make it stable. Activity Two Students will be given an introduction to Robolab and then will be challenged to program their robot to move forward and then to navigate around an obstacle, a small orange caution cone.
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Activity Three Students will be asked to take their tankbot apart, and then once their kits are back in order, they will be asked to build an original robot. Before beginning construction, students will be required to draw a sketch of their plan for their robot and label this sketch with their design elements. Students will need to show their designs to me and will only be allowed to proceed with my approval. Once their design is approved, students will be allowed to build their original design and then to test it by attempting the challenge in the previous activity. After accomplishing the challenge, each group will be asked to write a brief account of this activity and will be asked to share this with the rest of the class. This account should include a description of the robot, a critique of how their robot performed, and a justification of their design, which may include ways that given time they could improve it.
ANNOTATED BIBLIOGRAPHY Bridges, Towers and Other Structures set #9618. Bilund, DK.: Lego Dacta. This is the kit used in lesson two to build the bridges and structures. Carnegie Mellon Robotics Academy Robotics Educator. Windows or Macintosh Version Computer software. Robo matter incorporated, 2004. CD-Rom. A complete robotic classroom on a CD-Rom, this is a great CD to help guide new and experienced robotics teachers and coaches through teaching robotics. It includes investigations, curriculum, assessment rubrics, multimedia material and other robotics resources. Carnegie Mellon Robotics Academy Robotics Explorer. Windows or Macintosh. Computer software. Robo matter incorporated, 2003. CD-Rom. This CD-Rom contains robotic challenges ranging in difficulty, a Robolab tutorial for further help in programming, and additional multimedia material to aid in teaching Lego robotics. Cowan, Henry J., et al. A Guide to the World’s Greatest Buildings: Masterpieces of Architecture and Engineering. San Francisco: Fog City P, 2000. This is one of the books you could use in lesson two. Dietsch, Deborah K. Architecture for Dummies. New York: Wiley Publishing, Inc., 2002. This book is a great resource for vocabulary terms and definitions along with simple explanations of these terms for students. Dupré, Judith. Bridges: A History of the World’s Most Famous and Important Spans. New York: Black Dog & Leventhal P Inc., 1997. This book contains a nice glossary of terms and can be used for lesson two. Eberhart, Mark E. Why Things Break: Understanding the World by the Way It Comes Apart. New York: Harmony Books, 2003. This book is neat read that will be fun to share excerpts with students. It shows a real human side to physics and chemistry and is where I learned there is a difference between knowing why things break and knowing when things will break. EngNet. 1998-2005.
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Team Challenge Set # 9790. Bilund, DK.: Lego Dacta This is the Lego kit that we use to build most of our robots. Wilkinson, Philip. Super Structures: How Things Work from the Inside Out. New York: DK Publishing Inc., 1996. This is a cool book for use in lesson two; it has really neat cross section pictures of structures so you can really see how they are built.
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