Why do we need worms? Here is a fun and dirty spring activity for the kids. Build a WORM WORLD. All you need is Earthworms (ones you found, or night crawlers you bought at the store). Place the worms in a wheel barrow with fresh dirt and shovels. Also helpful, paper plates, magnify glasses and bug jars available for exploration.
Try this experiment: Can WORMS Smell?
Or build a Wormery - A Worm House
Here are 10 children's books all about WORMS http://happybrownhouse.com/2013/08/27/10-books-about-worms/