Did anyone ever visit Museum Village near monroe, New York? They have an old fashioned school house from over one hundred years ago, and you can sit in there and the “teacher” gives you a lesson about the way kids went to school. I think she showed us the stick they used, and she said there was the rule of thumb, that the stick could not be thicker than the teacher’s thumb.
The difference was that the teacher just rapped the kid on the knuckles, no punching and slapping around. It is sad that a teacher or rebbe takes out their frustration on the child. they need to be removed from their position. I remember watching one of my rabbonim with his kids, he never hit or yelled. just this one look!