First rules, make it safe and make it fun.
Once you get going, consider starting with stupidly light bows, just to show them how to draw, hold, and release. Where to and how to draw is weird, and a super light bow allows them to experiment very easily. I think a three under hold is better for learners. Point and shoot.
For ME. . . I learned that if I draw to an anchor point on my face, it could mean 26" or 29" depending upon my lean at the moment. I started drawing with my back until I lock my back (not to an anchor point), then settle in. This way I always get to the same spot and I can concentrate on the rest.
Using that easy bow allows them to do this. Once they know WHAT to do, a heavier bow is in order.
ChuckC