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 second day of the unit, students share homework, in which they collected evidence of a rain event with their families at home and they discuss how this evidence corroborates their claims. Next, students work collaboratively to describe and sort the digital pictures they took on the first day into student-generated categories. Last, with teacher support, they sort this evidence of rain as 1) evidence of changes to the land, and 2) evidence that shows no changes to the land. Then after observing and discussing two videos of slow and rapid changes water makes to the land, the students engage in scientific argumentation and sort their own pictures into 1) rapid changes and 2) slow changes to the land.