Sneaky Math

My music teacher in junior high once told us that if you show a little kid a big pitcher of water, then pour the water into a small pitcher, they won't understand that it's the same amount of water. (Don't ask why I remember that and not all the other important stuff I was supposed to learn...) The other day I tested this very theory on my son. He wanted a treat of mini colored marshmallows. I put five or six in a small bowl. They rattled around the bottom of the bowl and he immediately complained that I didn't give him enough. Right in front of his face, I poured the marshmallows from the small bowl to a tiny bowl and handed it to him. He smiled and said, "Thanks!"