Most of the kids who had a discipline problem at the private school at which I taught were actually refugees from the public school system - one I'm thinking of had been kicked out of her public school because she assaulted a teacher. She was NUTZ and should not have been admitted, in my opinion. But overall, I think students rise to your expectations.
And they are now reporting that the 9 year old "mastermind" of the plot threatened another student with the knife (I'm sure she deserved it
) and that is how the plot came to light.