The purpose of this lesson is to introduce the three types of bridges (truss, arch, and suspension) the class will study in this unit. After completing this activity, students should begin to understand how important it is to sketch a plan before building their bridge especially when the supplies are limited. The activity will also help initiate an understanding of the design constraints engineers encounter when building a bridge as well as the disadvantage of not contributing to the material selection.
Lab Activity
Materials
8 feet of string per group, roll of masking tape, a cardboard box, pencil, scissors, and a piece of paper
Procedure
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1. Students will break up into groups of four.
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2. Each group will obtain their materials.
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3. The group must construct a bridge across two tables or desks with the materials listed above.
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4. The group must design and sketch the bridge they choose.
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5. After the sketch is complete, the group will use the supplies and sketch to build their bridge.
Rules
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1. You may not talk to the group across from you.
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2. You cannot use any more material than what was given to you.
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3. Record any design changes you make when building your bridge and explain why this was necessary.
Post-Lab Activity
The students are to describe what they observed during this activity as well as some principles of physics. The similarities between engineering a bridge and building their model bridge will be noted. The three types of bridges will be described through various books, photos, and their models. Students should keep their notes from this activity so they can compare their methods of building with those of their final project in this unit.
Homework
The following written assignment is to be completed after the lesson: students will be expected to identify through their observations, some similarities and differences among each type of bridge and identify one of each type of bridge located anywhere in the United States with a picture including details of each bridge they have selected.
