Jacks is a children's game in which you bounce a small ball and quickly scoop up game pieces. There's evidence that some form of jacks was even played in ancient Greece.
Jacks goes by many names, including "knucklebones" and "fivestones." The original version was played with small stones, which were closely related to dice, and invented around the same time. In modern jacks, a player drops ten metal star-shaped pieces and then tries to scoop them up — first one at a time, then two at a time, and so on — after bouncing a ball, which is then caught before it hits the ground.