An animal's teeth an adaptation for the food that it eats.

Herbivore’s teeth:
(Photo shows lower jaws of herbivores, from top to bottom: moose, vole, deer.)
Plants are tough. Herbivores have teeth that are adapted to smash them up and get the energy out of them.
To snip off the plants stems herbivores use incisors at the front of the jaw (these are often missing from a found jaw).
To grind the plants they use their molars, which have sharp ridges on the top and fit together perfectly to smash the plant cells open.

From my deer skeleton: put the deer jaws in the skull to show how tightly the teeth fit together to crush the plants. Show how the jaw moves sideways to mash the plants between the teeth.
3D view of teeth in a mouse skull: https://www.youtube.com/watch?v=oLn70NiouS4

Carnivore’s teeth:
Carnivores need sharp teeth to catch prey and rip meat. Canines are huge, and even on domestic animals they can be terrifying (show cat and dog photo). Incisors are tiny. The molars are sharp to shred meat.
Look at real carnivore skull to see teeth (e.g. I have cat skull with upper jaw including canines)

Omnivore’s teeth:
We are omnivores.
Use a mirror to find the different kinds of teeth. (see notes)
Name incisors, canines, molars (use illustrations to show the different types)
Canines are there but small - between the two.
Incisors are more like herbivores though no where near as big.
Molars are between the two.
We are omnivores. Same as bears and racoons.