Life of Fred: Fractions by Stanley F. Schmidt

This book takes a slightly different approach. It tells a story -- a story of one day in the life of a five-and-a-half-year-old boy. All of the math arises out of Fred's life. All of it is motivated -- right down to when Fred is working at the PieOne pizza place, and he's trying to decide whether to put the tomatoes on the pizza before of after it's cooked and we get the commutative law. -- book (p. 8).