Jump in American Sign Language looks like a little person jumping up and down. You make you non-dominant hand flat to make the land. Then on your dominant hand, extend your middle and index fingers to make a little man, and jump him up and down.
You can use jump as part of a Simon-Says type game, where you ask your baby to do actions like jump, hop, crawl, walk, run, and stand still.
For physically active children, you can make a game out of using action signs such as run ,jump, hop, and be still, in a sign language Simon-Says type game.