Does the adult who monitors them work for free?
What will a couple of nine year olds do if they can get their hands on some weapons grade janitor tools?
When I was a middle school teacher, we had an annual day trip for our seniors to a dude ranch which ended in our "prom."
When we arrived the students debarked the buses, and after a quick orientation, were dismissed to go to activities, i.e. swimming pool, pool table, horse shoes, horse riding, volley ball, lounging around, etc.
When I was "making rounds" the desk told me that a group of student had checked out archery equipment and gone out to the range. I ran out and when I got to the range they had chosen sides and were having a "bow and arrow fight." For one of the very few times in many years of teaching, I blew my whistle!
Anyway, what Newt (he was a teacher?) forgets, is the application of Murphy's Law to education. He would farm out nine year olds to work in nuclear plants. What could go wrong?

--imm