Signing: To sign on, start with your weak hand horizontal and your strong hand at a right angle. Lower the strong hand so that it becomes flat on top of the weak hand.
It is like you have a switch and are lowering it onto the on position.
Usage: Use the on and off signs together to make a game out of it. Get a toy that lights up or plays a song. Switch it on and do the on sign. Switch if off and do the off sign.
Flash Card: Click the link to view the On Baby Sign Language Flash Card. The flash cards are printable and available in both U.S. Letter and A4 sizes.