Child or Children is signed by taking your dominant hand with palm facing down and bobbing your hand up and down in front of your body. The sign looks like you are patting a child on the head.
ASL for children looks like you are patting several children on the head. You take both hands out in front of you with palms facing down, and bob the hands up and down in front of your body.
Classification signs like child, baby, and adult are best taught at the same time, because the contrast between the signs helps to illuminate the meaning for your baby.
This is a contrast word that helps your babies understand age differences.