I was one of the first from our British primary school to go to a middle school, when the system changed in the late 1970s – previously, you stayed on until 10 at primary and then went straight up to secondary, but we went instead to middle school for three years.
It was a big change for us – our primary school had been fairly free and easy when it came to discipline, but we soon found out that things were very much less so at middle school. One big difference was the presence (or at least the threat) of corporal punishment. If you were really naughty, you could get sent to the headmaster for the cane (which was also in use at the secondary school).