Begin by reading The Lorax to the class. Take your time when reading to children, and hold up the book at each page so they can all enjoy the pictures. The pictures in this book happen to paint the story extremely well.
After reading, discuss with the class what kinds of things they can do today to protect our Earth. Encourage their thinking and creativity; afterward, be prepared to set up some beneficial classroom habits.
Start recycling bins. Every classroom can have a box for paper to be recycled. Some classrooms and schools are able to set up plastic and can recycling bins. (Glass is inappropriate because it can break.) When your students bring disposable plastics to school in their lunches, instruct them to rinse and place in the recycling bin, not the trash.
Take a field trip to a local recycling plant. Let the children see the amount of stuff that would end up in a landfill, but instead, it will be recycled.
Discuss various ways of reducing, reusing, and recycling with the class. Give the children big pieces of art paper and instruct them to color their favorite method. Then, display their ideas on the wall.