The mother of invention is right at your fingertips! Ten knuckles, two thumbs, two flat palms, and all those fingers—but our hands can be so much more. They were once the first pair of earmuffs, a primitive sun visor, and a convenient set of chopsticks. The work done by hands centuries and centuries ago has paved the way for many of our favorite and most useful tools. The always clever Andrew Clements reminds us all that the mother of much invention is right at our fingertips.