Teach your baby the signs for the words on and off in baby sign language with the following descriptions and videos.
Hold one hand in front of the chest with the palm facing down. Lower the other palm on top of the back of the first hand.
Hold both hands in front of the chest with the palms facing down and with one palm on top of the back of the other hand. Raise the top hand off of the bottom hand.
Beyer, Monica. 2006. Baby talk: A guide to using basic sign language to communicate with your baby. New York: Jeremy P. Tarcher/Penguin.