Remove a plant from its pot, keeping the soil intact. Explain how the plant's roots hold the soil in place. Introduce the term "erosion" to students. Explain how water, wind and ice cause erosion of soil.
Take students outside. Ask them to examine their surroundings and identify areas that have been affected by erosion. Common areas of erosion include edges of blacktop and around drain pipes.
Point out the placement of shrubs, trees and plant in relation to places that have been affected by erosion. Erosion is less likely to be visible in areas with plant and tree life. Explain that this is due to the root systems holding the soil in place.
Fill an aluminum pan with soil. Pat the soil to firmly pack it. Add rocks to the soil and press lightly to keep the rocks from moving freely. Insert a book under one side of the pan to create an incline. Pour small drops of water onto the highest point of the pan, over the rocks and soil. Instruct students to observe the effect the water has on the soil. The soil and rocks in the top part of the pan will begin to migrate to the lower portion of the pan.