In a private school, that's probably a decent solution. Generally, people willing to send their kids to a private school are probably the parents who (a) put a

In a private school, that's probably a decent solution. Generally, people willing to send their kids to a private school are probably the parents who (a) put a premium on their kid's education and (b) make their children behave at least somewhat civilly most of the time. That cuts out a lot of the problem cases of children who face no consequences at home and who have no incentive to learn. Private schools also get to select on competence in many cases. You're not going to have someone who's reading on a 4th grade level in your senior English class, as happens at public schools. And you can refuse hard discipline cases and/or expel them, which they can't do in public schools. In that environment, a teacher should be able to control the students. But you can't expect a system that works in those conditions to work in non-optimal conditions.