With almost half of Americans relying on groundwater supplies, it is more important than ever to protect aquifers from possible contaminants. Working in small groups, young environmentalists explore this problem as they create an aquifer model and use it to perform a series of investigations. Though somewhat complicated, this working model clearly demonstrates the flow of ground water and the movement of pollutants through the environment, making this an excellent addition to a high school earth science unit on the hydrosphere.