This would seem like a very unpromising time to call for volunteers, but little Kylie is just one of many willing helpers. To the obvious disappointment of some of the boys, her arm does not come off, no matter how vigorously it is waggled. Clearly teeth are different from the rest of our bodies.
But they are similar across a whole range of animals, some of which now put in an appearance. First using sounds - rain on forest leaves, wind in the mountains, waves at the seashore - to set the scene, then through the magical medium of shadow puppets to bring deer, sharks, foxes, snakes and elephants into the little city school; and finall through tusks, skulls and teeth that once belonged to the animals themselves.
"You can't talk down to children," says puppeteer Eva Melrose. "Even young ones know an awful lot already. But you do have to pitch it at their level. So although we try to make it informative, by telling them how to look after their teeth and what foods are good for them, we also make it fun too and try to stimulate their imaginations."
The other characters in this appealing show are Grace Surman, whose rapport with young children makes her a delightful dentist, and Mikey, who starts out as a funny-looking doll with a big mouth and ends as a little boy with similar problems to the children, many of whom would clearly like to take him on to their next class.
But three performances a day rule this out, so as the children head for the door with some still conducting their own experiments - "Maybe if I pull this arm a little harder it will come off" - Mikey heads back to his box, where he and his wobbly teeth will remain until he comes to life again for the next performance of Don't Forget Your Toothbrush.
The Edinburgh International Science Festival schools programme runs until the end of March. To book a show, tel 0131 555 6626