Why do your eyes blink? Why does your heart race when you run fast? How does your body know when to stop eating? This box set of 6 encyclopedias about the human body will answer these and many more whys and hows for you.Learning is made simpler with well-labelled diagrams and an extensive glossary of difficult words.Bonus: the books in the box set come loaded with Isn't It Amazing—a section of fun facts to keep you glued for more.