This is a 3rd grade lesson plan with worksheet and PowerPoint. You can easily, however, adapt this to a lower or higher grade level if you wish.
In this lesson plan, students learn how harmful littering can be to the environment. Then, students will learn the definitions of reduce, reuse, and recycle and learn how to do each using the sample garbage you threw on the ground.
This lesson took my class about 60 minutes because of discussing their pictures; however, you know your class.