20y ago I did a high school semester in the UK (Worthing) and it was a very good environment with no bullying whatsoever. 3 factors contributed to this:
1) low stress environment as a whole (beautiful campus, calm teachers and staff, etc)
2) the students had a high degree of liberty in choosing what classes they would attend, so they were presumably interested and not rebellious
3) the student divided themselves into strict groups, and these groups barely interacted with each other.. so after class the 'goths' would hang with the goths, the 'sports-people' with the sports-people, etc. I didn't quite like this at the time because I'm very sociable so it struck me as weird. However, it did work in the sense that there were hardly any social problems among the students.