STOP! Before you do another thing: 1. Make a funny face. 2. Hop up and down on one foot five times. 3. Scratch your head with one hand and pat your stomach with the other. Now, turn the page."" When you've turned the page, you're told that you used cheek, leg, hand, and arm muscles to perform these actions. Showers' simple explanations of biceps and triceps and skeletal muscles are similarly introduced. (""TRY THIS. . . ."") Once he's got kids involved in relating his anatomy lesson to their own actions, Showers explains the difference between skeletal and smooth muscles, notes that ""your heart"" is a third kind of muscle, and reminds readers that exercising is good for skeletal muscles. It's a well structured first lesson, and Barton's pictures are appropriately loose, clear, and cheerful.