With this book, kids will learn how screws work, where they're found, and their uses throughout history. They will learn that screws are simple machines that convert rotational motion into linear motion. A simple wood screw is made up of a metal shaft with a thread spiraled around it and a head with a groove in which a screwdriver can fit. When rotational motion is applied to the head of the screw, the screw converts the force to linear motion, which in turn drives the screw into the wood. Wood screws are just one example of this versatile simple machine, which will fascinate your budding scientific thinkers.