Signing: Share in sign language looks like you are dividing something up into portions. You take your weak arm with hand open and perpendicular to your body with thumb pointing up. Your strong hand will make a loose T-shape with your weak hand and will wave back and forth as if dividing up a little pile of morsels.
Usage: The concept of sharing can be reinforced with older toddlers by using the sign. Remember share, should not apply just to the toddler sharing their things with others, but also with you sharing with your toddler. By modeling sharing with the toddler, you show them that sharing is something they should want to do and that they gain by sharing.