” attacked for at least two class periods, “
When I was in Junior High one class period was about 55 minutes long, give or take. We had five minutes to get to class then another five for the tardy bell. Don’t know how it is today.
Mind you this school has security guards and most likely cameras and they did not catch this.
Or maybe the kids are having sex all the time in 'discreet' locations in the school, so this just didn't draw their attention.