Set up collections for used paper throughout the school. Reuse the backs for scrap paper, or excess paper can be sent to the art department to be made into homemade paper. Make a point to use less paper throughout the school day. Consider using the chalkboard and white erase boards instead of scrap paper.
Institute waste-free Wednesdays, or Trash-less Tuesday at school. Encourage kids to bring in reusable containers rather than excess packaging. Try to cut down on the amount of plastic and polystyrene in the cafeteria. Measure the trash generated at the end of lunch and track the difference from week to week.
Form a giant aluminum foil ball. Starting at the beginning of the year, challenge classrooms, grade levels, or even a rival school. Have the students bring in the leftover foil from home, gum wrappers or from cafeteria meals. Build the ball throughout the year. Weigh to determine the winner. The balls can then be recycled.
Teach children a lifelong skill and beautify your school with outdoor gardens, or grow herb gardens in the classroom. Aside from the science learned, children can discover the history behind plants and the many uses of plants and herbs.