Objectives and Rationale
Teaching math can be like that Far Side cartoon where a dog is looking quizzically at a talking man; from the caption bubble we learn that what the dog hears is "Blah, Blah, Blah". Ever wonder just how many students are tuning out during math instruction or not understanding a word you say? Traditional methods of teaching mathematics as a disciplined study obviously fail to motivate a significant portion of students today and if you are at this website searching for lessons you have likely figured this out. I dedicate this unit to all the students that have been asking for a follow up to their previous bridge building experiences in elementary school and to everyone in the Yale Teachers Initiative on Bridges for their excellent suggestions regarding this unit.
This unit for 8 th graders, (good for grades 5-8), will address through a history of great thinkers the development of understandings about forces and give students a variety of opportunities, including hands on activities, to demonstrate and experience the dynamics and equilibrium of forces in bridge structures. It creates opportunities to develop understanding of balancing equations through looking at and working with cantilever bridges. Specifically, the lesson will use cantilever bridges to work with the equation force times distance from a fulcrum on one side must be equal to the force times the distance from the fulcrum on the other side, to be balanced. It will use this formula in its ratio form as well to solve for one unknown through the use of cross multiplication. Additional activities address proportion and measurement through students' scaled bridge and truss drawings, and graphing through plotting the stress vs. strain of various materials, (fishing line of various weights, string, wires). Students will begin to work with the following science concepts: force, compression, tension, stress, strain, elasticity, and plasticity. Use of these terms and concepts will be developed and practiced throughout the unit. Finally, this unit on bridges develops students' understanding of how math and engineering is used in the real world through examples, hands-on experience, and interacting with architects and engineers. For an example of standards covered, see Appendix A for specific NM standards covered in this unit.
The goal of this unit is to integrate mathematic standards into a unit on bridges but it could also be considered a science unit that integrates math in a unit on bridges. The art has been left in the unit's title for the importance of aesthetics in design.
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