To teach young ones about pollution, I have each child bring in a piece of recyclable garbage. We sit around a pretend pond (a large painted blue sheet of butcher paper) that is filled with paper fish. I tell a story about how the fish live in the pond surrounded by the beautiful woods. As people visit the area for picnics, they begin to throw their trash into the water. I have the children do this, one at a time. As more trash goes in, the fish of course have to come out. Soon the pond is full of garbage and no fish. Now I ask the children to help clean up the pond by removing their garbage and placing it into appropriate recycling containers. These I have made ahead of time by taping commonly recycled items (newspaper, glass bottle, plastic container) to the outside of a paper bag. We feel really good when the pond is clean and the fish can come back to swim there.
Let each child plant flower seeds in a cup with potting soil, and watch how mother nature works. Keep by window for sun light.
Take children on a study trip to a recycling plant to learn more about the importance of recycling. This will also give them a chance to see the process by which it is done.