The students are sculpting the sand into hills, valleys, mountains and other
landforms. Paul would later place a plastic tarp over the landforms and then spray
water upon the plastic tarp to simulate a watershed. As the misting water landed on
the landforms and ran down the tarp, lakes and rivers would form below. Students
were able to see for themselves that polluted rainwater (acid rain) can then flow
into our lake (background) and then into our water and food supply.