What I really enjoyed about doing this activity with 6th graders (compared to the 4th graders with Pumpkin Elevators), was that the Science concepts were understood on a deeper level. The students made connections quicker was that the tallest tower isn't necessarily the most structurally sound. Their designs at first greatly different from their end designs!
Just to point out how much I love students who not only think like me, but take it one step further. Below, the picture on the left with the blue bin shows how I gave the materials to students. The picture on the left shows 2 bins after they had been reset for the next hour. Clearly, the purple bin makes me swoon! The red on the other hand...well..at least they got everything back in the bin. :)