Jessica and Jed are hoping to ride in Uncle Sam’s tank. But when they go to visit him, they discover it doesn’t work. In fact, it’s in pieces! luckily, Uncle Sam knows how to repair it. Join them in their quest to rebuild the tank, and along the way discover the science of the machine and what makes it work.

WHY THINGS DON'T WORK is a series of books that present a comic story to show how machines work— from the creator of 

‘Brain Surgery for Beginners’, ‘53 1/2 Things That Changed the World’ and ‘Answers to Questions You Always Wanted to Ask’.