[pwhelan]

Part of it is that back then if a child was acting up, they would get disciplined at school and then disciplined ten-fold at home.

It is a lot easier to teach a room filled with children who are willing to put in the work or at least not screw it up for the other children. It is a lot easier for a teacher when he/she can kick a child out of class for misbehavior and the teacher is protected rather than chastised.