Pupils will learn how heavy rain runs down storm sewer drains or by passes wastewater treatment plants through overflow directly into nearby lakes and rivers, taking pollutants and excess nutrients with it. Ask them if they know that our streets are directly connected to rivers and lakes and if they know how.
Prepare an experiment:
Hold a cookie tray (representing hard surfaces, such as roads, parking lots, roofs, ) at an angle over a bowl and spray it with water (representing rain or melting snow). Explain how the rain runs off the hard surface into the “lake” (bowl). Ask pupils to think of different examples of impermeable surfaces that allow water to run off.
Add “pollution” to the surface, such as bits of paper (for litter), vegetable oil (for motor oil) or colored water (lawn chemicals) or bits of leaves (for organic pollution). Repeat the “rain” and watch the pollution run into the lake (bowl).
Add a sponge to the impermeable surface and repeat the rain, watching the “natural area” absorb some of the rain. Ask them what the sponge represents (floodplains, retention areas, gardens, parks or other areas where rain can soak into the ground).
When it rains, the storm water that runs off our driveways, lawns, houses, and parking lots can carry pollutants, such as oil, paint and chemicals and excess nutrients found in grass clippings, leaves and pet waste, down storm sewers. Storm sewers drain directly into nearby lakes, streams and rivers where the pollutants and excess nutrients can negatively impact water quality, plants and wildlife.
We can protect water resources by taking steps to reduce runoff and let rainwater soak into the ground where it can be purified. Explain to them that helping water to soak into the ground next to houses and other buildings helps to prevent pollution of surface waters.
Materials and Worksheets
cookie tray or other hard, flat surface that water cannot soak into
large bowl (clear glass is ideal), bucket, or another container for water
spray bottle with water
different items representing pollution: small bits of paper, vegetable oil, pieces of green leaf, large sponge or cloth