In this four-lesson unit, students collect evidence to construct explanations that rain causes changes to their school yard. They develop models to explain rapid and slow changes to the school yard, and observe these changes at a broader watershed level. Finally the students apply the information to an engineering problem where they use their model to develop a solution that will slow down or stop rainwater from changing their school yard.

In this lesson, on the third day of the unit, students use evidence to construct written claims that rain can cause changes to the land. They describe all of the different surfaces on the school yard, and then predict how the rain flow will interact with each of the different surfaces. Next, the students conduct investigations to collect data about the effect of water flow on different types of surfaces (black topsoil, woodchips, etc.) of the school yard. In small groups, students use the data to develop an evidence based claim that explains relationships between water flow and the changes caused to the surfaces. At the same time, students build connections from previous observations about rain and water flow to deepen understanding of the interaction between rain and surface materials.