Everyone knows that the knee bone is connected to the shin bone, but they probably don’t how the two are attached— by springs, bicycle gears, and very sticky duct tape! After all, kids are complex creatures, complete with trap doors, bungee cords, and, of course, lightbulbs (for when they have good ideas). Alan Snow’s classic tongue-in-cheek sense of humor gets an extra boost from actual tongues and cheeks, and his clever illustrations of kids’ inner workings become the backdrop for hundreds of real-life—and really astonishing—facts about the human anatomy.