Argh! There’s a Skeleton Inside You! by Idan Ben-Barak & Julian Frost
Quog and Oort are two friends on their way to another friend’s birthday party when their spaceship breaks down. They try to get out and fix it, but they cannot because Oort is a gas cloud, and Quog is a jelly blob and they cannot open the door. You, the reader, are asked to put your hand on the page and Oort is able to reveal that you have a skeleton inside you! You can help Quog and Oort get out and fix their spaceship by using your bones, muscles and nervous system to push pages, lift the book above your head and even show how you can turn a page with your eyes closed.
With lively, bright and simple but informative illustrations Argh! There’s a Skeleton Inside You! is an excellent (and funny) introduction to basic anatomy for kids aged 4+.