The idea of this game is simple - split your group into teams of 3 or 4, and give each team a "Building Kit" (explained below) and a bowl of water. Each group has 30 minutes to build a bridge to span across a bowl of water.
At the end of 30 minutes, each group has to demonstrate their bridge. You then test it for strength by adding pebbles one at a time, until the bridge collapses. The team with the strongest bridge wins!
The Building Kit is a shoebox with a variety of building materials. For example:
Make sure each group has the same amount of materials, just to keep things fair.