Student work on air pressure
and forces involved in the motion of cars, tricycles, and
wheeled LEGO designs.
Pictures of the activities
during the project.For testing, a bucket was suspended from each bridge and filled with bricks and other weights until the bridge started to fail (or the student opted to suspend the test to avoid destruction).
To compare designs, the "cost-effectiveness ratio" was calculated by dividing the test load by the number of sticks used (assumed to cost $1 each). After the testing, the students were encouraged to think about and discuss the forces in the bridge elements; in the case of these particular designs, compression and tension were the easiest for the students to discuss.
A student explains forces in her bridge.
(QuickTime Movie - 648K)Zack, after thinking about what constituted a good bridge, went home and built the better bridge. It would not break even though he put all the weights into the bucket. We didn't count this bridge in our graphs and calculations, but we were all very impressed.
It naturally took many sessions to carefully look at and talk about twenty two bridges, but the class was enthralled. It was a great assesment of learning to hear all the student evaluations.