Spin off from the childhood injustices thread...
Loads of people in there saying they had to do lines - I never once encountered this, I remember reading it in books when I was younger and assuming it had died out in the Victorian era, or faded along with corporal punishment (or just an American thing, because Bart Simpson does it).
But maybe my school was weird, because we didn't have after-school detentions either - it was a rural school and most people got school buses from the villages, and the school knew that if kids missed those, and the parents had to come pick them up later, then the parents would kick off - not at the kids, but at the school. I think there might have been lunchtime detention, but don't think it ever caught on.
The couple of times I got told off, I had to stand in the corridor outside the classroom, or go see the head of department who would tell you not to do it again. I guess beyond that they sent a letter home or something?