They have sensitive respiratory systems, fragile bones and their health can go downhill from one moment to the next. Bunnies are crepuscular - they awake and become active in the early mornings and evenings. They sleep the rest of the day while we are at work. You can play with them and love them before going to work and after you return home. Bunnies have sensitive ears and, no matter how quiet kids are, there will always be noise in a classroom and a teacher talking most of the time when the bunnies are supposed to be quiet and sleeping.
Bunnies like to chew on anything they find.
Even knowledgeable rabbit caregivers have had this happen accidentally in their homes, so imagine the chances of a bunny encountering these dangerous items with lots of kids around. The potential risk is multiplied by the number of children in the classroom. Bunnies have very sensitive respiratory systems. Many things can happen when you leave the bunnies unattended. There are cruel people everywhere.