On a visit to the zoo, a young boy counts the animal babies and parents in each enclosure, the accompanying rhyme encouraging readers to do the math along with him. “Two tiny peachicks / gather round peahen. / Add one papa peacock. / How many in the pen?” Slade slyly sneaks in some great vocabulary, working the animal baby names into each verse. Equations appear on the corner of each page. Waites provides plenty of details—the borders of each spread are elaborately decorated, while the illustrations arrange the animals naturally (if rather stiffly), resulting in some challenges in spotting each critter. A final spread encourages readers to count how many animals they saw in all at the zoo. Backmatter teaches two methods for adding all the numbers, a section about fact families and a matching game wherein readers can test their memories of baby names against some paragraphs of information about each animal’s development. The solid math and informative backmatter make this a worthwhile addition to libraries and math programs. (Picture book. 5-8)