The Number Devil A Mathematical Adventure
by Hans Magnus Enzensberger
Ok, kind of a strange text book. A kid actually looks forward to going to bed at night and dreaming of... math!!! Normal children dream of Nintendo, superheroes, Hanna Montana, but this one does math problems in his sleep.
It's actually a cool book; I did not understand all the concepts and explanations, but I don't have to understand it to teach it, do I? There are lesson/game ideas to make math "fun" and it's a different way to introduce and explain decilmal, factorials, and dividing by zero... some kids could probably get a lot out of it just from the engaging story, and learn something almost accidentally.