Take the class outside to where the stream table is set up. Have the students draw and describe the stream table. They should note the amount of soil, its placement and thickness, and the angle of the table. Slowly and consistently, pour water down the table. Continue to pour until a fairly large pile of soil has washed to the bottom of the table.
Gravity pulls water down a hill.
Erosion is the deterioration of the soil as water carries it away. Note that, in nature, vegetation provides resistance and slows water. Less erosion takes place, as leaves diminish the force of falling water and roots hold the soil. Return to the classroom to discuss areas around the school, neighborhood, or town that have been eroded. Lead them in a discussion of how their new knowledge would affect their choice of homes.