The books in the Know Your Body series offer young readers a variety of age-appropriate ways to become more familiar with various body systems. Each book introduces the system and briefly explains its structure and how it works. The books then provide more specific facts and details. Although the design, illustrations, and photos in the books do not have the most up-to-date look, the content is relevant and interesting. Your Heart describes not only the structure and function of an adult heart but also its weight out 12 ounces, equivalent to the weight of two small apples. The books nicely balance a focus on science and on personal health, including some material on keeping the body healthy. The relatable text lives up to the series title, as they truly help young readers know their bodies.