A Sign Is Built From Parts

Two signs, side by side, that mean completely different things - and only one thing about them is different. A child who knows no sign language at all can find that one thing, three times out of three, because the parts a sign is built from are visible before any of it means anything. Change where the hand goes and mother becomes father. Change the shape of the hand and candy becomes apple. It is the same trick as changing pat into bat - except that not one of these parts is a sound.