"Why do cows wear bells? Because their horns don't work." Kids never tire of old-school jokes, and readers 8 to 12 will have much to savor in this compact set of three books, each containing 300 knock-knocks, question-and-answer jokes, tongue twisters ("Skunks sat on a stump and the stump stunk"), and more. It is National Geographic, so count on color photographs of animals throughout—many of them look like they're laughing—and this generous set includes a poster as well.