We talked about what we would look like without our skin, and that our skin helps keep our insides in and clean. "OOOOO, YUCK!" they said. "We would be slimy and gross." So we did an experiment.
I gave them each a sucker with the wrapper still on (our skin). I asked them what would happen if we took the "skin" off the sucker and took it out to recess. This really got their attention.
We took the "skin" off and went outside and played. This really helped them visual the importance our our skin and germs. If we didn't have skin to help keep the germs and dirt out, we would be a mess.
They were totally disappointed that they could not eat their sucker, but don't worry, we came back in and ate a clean one.