Prisons would be a lot safer if the dangerous inmates got kicked out of prison and left behind the ones who didn't attack other inmates.
If you want to improve schools quickly, expelling problem kids is the easiest way to do it. But that would cause consequences to the expelled kids, as well as society.
"Your kids should take one for society" is an atrocious pitch.
"Your kids should be stuck with people who ruin their lives because criminals are" is also terrible.
The correct response is moving problem kids to problem schools, then to disciplinary schools, and if necessary to juvy.
Put people where they belong, with the people they belong with.
Otherwise the people stuck with the trash will leave (and maybe that's okay in the end)
Often dangerous inmates are moved to higher security prisons. Gang members are segregated, etc.