I agree with Lyn, the health and safety brigade will have a field day when they find out you gave 20, 8 yr olds very long and sharp barbed needles. Wet felting would be much safer, you could still make bunnies and either an adult could needle felt th pieces together or the could be sewn on.
very definitely I would go with wet felting. All you need is one stabbing another. The problem with a class is there will be some that will not be interested so will not pay attention and start doing something they shouldn't.
All valid points and appreciate the feedback. I have decided not to offer the needle felting and stick to wet felting flowers, landscape and smaller projects. I am still working with the girl in the class now and she's working alongside an adult or me at all times so we're keeping an eye on her.