Take an informative peek at these all-important strips of stretchy tissue; in Muscles, for kids, first up is a diagram showing the most important skeletal and smooth muscles – as well as your major cardiac one – that allow you to move, digest food, and also keep your heart pumping. The fine distinctions between voluntary and involuntary muscles are next, and kids can then trace a diagram showing the “anatomy” of action, which relies heavily on nerves.

Here’s a great activity to try: Contort your face into various expressions, like pain and surprise, and try to pinpoint the exact muscles of your face responsible for these subtle motions. Are you stumped? A (somewhat scary-looking) diagram peels back the skin on your face to display the complex arrangement of muscles that convey hundreds of emotions. More fun things to try: isometric and isotonic exercises, and simple tests that demonstrate the wildly different movements made possible with muscles. For kids who want to know what happens when your muscles don’t behave, descriptions of Parkinson’s disease and other muscle breakdowns are also featured, and the whole thing wraps up with an eye-opening discussion of animals and their unique muscular systems.