He wore his special Earth Day shirt.
If you can't see it, it says "Respect Your Mother" and the "O" is a picture of the planet Earth. I bought it from Crazy 8.
Lastly, at bedtime, we read The Lorax by Dr. Seuss. This is my son's favorite book, and we read it every night, but it offers another great message about taking care of our planet.
This is also a book I read with my fourth graders at different times throughout the year. I use it to teach setting in Reading and human/environment interaction in Social Studies.