Expansion: Have students theorize what a water wheel like this could be used for. Have them try to develop a simple machine that could be attached to the wheel and moved via the water, then record their findings. Have them vary the rates of water flow to determine how it effects the wheel.
Expansion: Have students vary and record the amount of air inside the balloon to see how it effects how far and fast the hovercraft moves. Set up a fan to see if air currents effect movement.