There was this kid who was always in trouble at school; fighting, not doing his work, breaking things, cursing at the teacher. He was thrown out of every public school in the region.
As a last resort, his parents enrolled the kid in a Catholic school. His bad behavior ceased immediately, and he became a model student. His parents asked him why.
The kid told his parents that when he saw the man they had nailed up on the wall at the Catholic school, he knew that he better change his ways before they nailed him up on a wall, too.
Years ago, I worked at a catholic hospital. One day I had my kids with me and we walked past the chapel. My youngest, 4 at the time asked, "Who is that man and why is he stuck to a t?"
After laughing, I told her it was a puppet.
I was a teacher (Science, PhyEd) at a Catholic 'middle' school for one year.
The principal was a very likeable nun, the students feared her.
Two 'vignettes'
I was given (by other teachers there) this "procedure"
If the class/student was getting "unruly", take the 'worst offender' out into the hall for a 'chat"
BANG the locker LOUDLY so the entire class would hear (not see) it, then send the student to the principal.
At a parent teacher conference -- three teachers, both parents -- for the 'behaviour problem' in my homeroom (6th grade), the father (pounding his one fist into the other palm) said "If my kid gets out-of-hand LET HIM HAVE IT!". I'm thinking 'No more wondering why the kid has problems'