To sign ball, put the fingertips from each hand together with your palms separated but facing each other. You will look like you have a grapefruit-sized ball in your hands. Now move your hands apart and together, so your fingertips separate and then touch again.
Ball is a great sign to learn for infants that have a favorite toy ball to play with. Every time you introduce the ball into play, say the word ball and do the sign. During play, keep finding ways to say ball and do the sign. “Roll the ball to Mommy,” or, “Sarah, do you want the ball?”
The sign for ball is super easy and extra useful. Many babies develop interest in balls early on. Teach it in the context of play and using the flash card.