Fifty years ago nothin. I'm 36, so 20 years ago it was still perfectly acceptable to swat a child. Our parents had to sign a form at the beginning of each school year stating that mild corporal punishment could be administered.
The kids whose parents refused to sign ran wild. Not a surprise. I, whose parents signed in large red letters, behaved myself until I got to high school, where they didn't pop - they only gave "sparkle duty." (That's picking up the cafeteria for roughly five minutes after lunch.)
I'm 61 and went to the same segregated school for 12 years, we never had any of these problems. If you 'acted-up', you got spanked by the principal and then again when you got home by and even madder father.