Water is notoriously hard to control. Driven by gravity or pressure it can squirt through the smallest opening, and in large volumes it carries incredible destructive potential. As a result, dams built to stop or divert the flow of water must be both impermeable to water and able to resist great force. In this video segment from PEEP and the Big Wide World, children experiment with various materials and designs to see if they can create a dam that meets the challenges of their specific circumstances.