Counting by twos gets a little animalish in this tale of a rude bovine traveler. A driver with room for 20 passengers counts each pair as they board his trolley. Ducks, geese, sheep, pigs, and horses all climb up and find seats. But when a herd of kids boards, a cow cuts in line and the driver loses count. The weary cow asks each pair in turn if they have enough room. As they respond affirmatively, she demands they “mooove over” to make room for her, her bags, her picnic lunch, and her beach chair. When the driver notices the passengers on the roof and only the cow left on the trolley, he ejects her as “one too many.” Meisel’s colorful illustrations fit the tale perfectly, with the sweet facial expressions of the cow lending surprise to her rude behavior. Not only will readers learn to count by twos, they will also learn the words used to describe pairs: duet, couple, twosome, partners. The final page lists five other math-related activities that can be used to extend the concepts in this funny story. (Picture book. 4-8)