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Building Bridges and Engineering Design
Smart Start: Before beginning the lesson, teachers should give a brief overview of different types of bridges, the importance of bridges in terms of their design and demonstrate that there are a lot of considerations to take into place when building a structure that must hold the weight of multiple types of vehicles. A good story to se is the Tacoma Narrows Bridge Collapse in 1940 https://www.youtube.com/watch?v=mXTSnZgrfxM (2:22-6:00).
Split into pairs and sketch out the bridges such that you can see how many pieces and how long the pieces you’ll need to use should be. Below is an example design of a bridge. The blue lines represent the straw pieces and the green markings are the pipecleaner.
After designing the bridge, start cutting up straw pieces and bending the pipe cleaners to help connect each straw.
Attach the pieces together as designed your sketches
Now place each bridge between two suspended platforms such that the bridge is off the ground. Use a small bag of common materials (LEGO pieces, pencils or other classroom materials) to create a small weights. Place the weight on the bridge and afterwards write down a description of how the bridge faired with the weight and attempt to measure the drop/ bend of the bridge for a given weight. Continue increasing the weight to test the limits of the bridge.
To conclude the lesson, each of the students must describe their bridge and why they chose the design that they had at the end. Also, describe how the bridge fared against the weights and mention any alterations to make the bridge even stronger.