David A. Adler explores fractions in action at a birthday party, which provides ample opportunities to examine pieces and parts. A clown at the party holds ten balloons, three of which, or 3/10, are red. When the birthday cake is cut into twelve slices, each piece is 1/12. Building on these and other examples, Adler goes on to explain more about fractions, from terminology such as “numerator” and “denominator” and what they indicate to how different fractions can equal the same amount (e.g., 2/3 and 8/12). Brightly colored graphic illustrations by Edward Miller depict the partygoers and entertainers and provide clear visual examples of the concepts addressed in Adler’s lucid narrative. (Ages 7–10)