Laurence Pringle’s children’s book on evolution, Billions of Years, Amazing Changes: The Story of Evolution is just out. I can recommend it not because I wrote the foreword (which is very short), but because it’s well written, well illustrated by Steve Jenkins, and I vetted it for scientific accuracy as well as making suggestions to the author about useful things to include. I think the final version came out nicely.
If you’re curious, the Amazon link above gives you the chance to look inside for a fairly thorough preview.
I think the book is intended mainly for children in school grades 4-8 (ages 10-14 in the U.S.). If you have a younger child and want to teach them about evolution, I can recommend Pringle’s book, and then Dawkins’s when they’re a tad older.