Teeth are white

At Graeme's school they did a lesson on brushing your teeth and the teacher gave the kids cut-out pictures of teeth and a toothbrush to color. They glued them to giant popsicle sticks and hung them on the class bulletin board. Everyone's teeth were colored except for Graeme's. The teacher reported that he wouldn't color the teeth because he said that teeth are white. My child is either very matter-of-fact or a pain-in-the-ass.