Questa Bridge Falling Down
Questa Middle School science class sponsored a popsicle stick bridge-building competition between the 6th, 7th, and 8th grade science classes. The objective of the competition was to see which team of students could build the strongest bridge to span a one-foot gorge. The rules of the competition were that it could only be built of popsicle sticks and Elmer’s School Glue.
Each class was divided into two-person teams. Students got to choose their teammate. Each team was initially given 50 popsicle sticks and a bottle of Elmer’s glue. We quickly found out that 50 sticks would only create a skeleton structure. Eventually the students used 6,000 sticks, between 35 teams. They ran through 13 bottles of glue plus a quart-size refill bottle.
Part of the project was to draw out a template that they would try to create. Students then started gluing sticks together, which brought on the first challenge. If you don’t know how slow Elmer’s School Glue dries, I know some students who will advise you. It is very slow. Putting together elaborate bridges in a fixed amount of time caused multiple adjustments in design.
The next challenge was to figure out which way a popsicle stick needs to lay to maximize its strength. They learned that laying a stick flat was easy to break, while standing on its side gave it much more strength. We studied some truss designs and how the triangle shape was used because of its strength of design. Adding vertical sticks to each triangle really beefs them up. After several hours of intense concentration and a weekend drying time, the day to break bridges arrived.
Monday morning the scene was set. Two tables were placed a foot apart and the first bridge was placed across the gap. A small chain was looped through the bridge, suspending a bucket underneath. Water bottles were then added one by one to the bucket and no one knew when the critical compression weight would collapse the bridge.
We ended up having to go to a janitor-size bucket that would accommodate 30 water bottles plus a 1-liter water bottle. This weight only broke a few of the lighter bridges. Eventually we had to add a box on top with multiple science books to break the heavy-duty bridges.
Each class ended up with a class survivor, which will be entered into the finals. We are waiting for one of the teachers to bring in 80 lbs. of barbells for the finals.