How about some fun games to fill the space between planting trees and making a bird feeder? Here's some suggestions for you to try out.
- https://www.infoplease.com/games/hangman/green-awareness
- http://www.primarygames.com/holidays/earth_day/games.php
- http://www.dltk-kids.com/crafts/earth/games.html
- http://mylifeandkids.com/22-awesome-earth-day-games-for-kids/
- http://www.livestrong.com/article/172572-environmental-outdoor-games-to-play-with-children/