Good question, Emile.
We're really big fans of the Why Should I...Series Written by the aptly named Jen Green and Illustrated by Mike Gordon. The titles in the series include: Why Should I Recycle?, Why Should I Save Energy?, Why Should I Save Water? and Why Should I Protect Nature? All of which are questions which children and adults need to ask themselves and answer.
The books, by the World Wildlife Fund, are geared at children ages 4 to 7 and teach children the value of eco-living in an approachable, easy to understand way. Each book also features suggestions for parents and teachers on how to expand on the subjects covered.
Are there any other green children's books you can recommend to Emile?