Bit of a quick google:

http://www.earthskids.com/cooking_with_kids.aspx

There's a book on amazon for like $10 called The Math Chef. Judging by the absence of the 's' on the end of math, it may be American though.

I had a really hard time with maths in secondary and primary school, and cooking was the absolute best way I could have learned and built my skills, it really worked in helping me retain the info...and the food was yum. My mum just used the Nursing Mothers Cookbook, all the recipe are so child friendly and simple. I ended up buying my own copy when it was reprinted.