There are a lot of great ideas in this "Earth Day Mini-Unit" by Rachelle Smith
A couple of great math games in this download by Games 4 Learning
Cute ABC order activity by: More than Math by Mo
And this one is mine - cute Earth Day writing paper!
Comes in 2 versions, this one is for older kids, and the other version for younger kids has less lines and space to draw a picture. Prompts could be "Why I love the earth..." or "I can help the earth by..."
I hope you find something useful for Earth Day! Enjoy the freebies!