The adolescent instincts brought most fully into play in the public school social setting are the instinct to conform, and the instinct to enforce conformity. Want to torture your public-schooler? Make him wear a dorky hat to school.
Any non-conformity is siezed upon and seen as a weak spot, an entry point for ridicule. Take away the adults, and before long you've got Lord of the Flies. Heck, you sometimes get that with the adults present, depending on the adults.
However, this urge to conformity is not discouraged by the school system. In fact, one could argue that the architects of public education designed the environment to encourage it.
My daughters' new public school did reach the "Lord of the Flies" levels last year.
Most of the time the kids ate outside (we live in California). The school does not even have an indoor cafeteria. Well, it does rain here, and the first rainy day was a total disaster.
They had the kids go into the gym, and sit on the ground and eat. The kids started going crazy. They were running around wild, screaming at the top of their lungs, and throwing food.
I didn't trust the school, so I went at lunch time. I wouldn't let my kids go into the gym. Thank God, my daughters' teacher saw what was going on and pulled her kids out of the gym and took her kids to her classroom. Most of the teachers didn't do that because they didn't want to give up their lunch break.
I could maybe let this slide once, but I would expect that it would never happen again. Well, this wildness in the gym happened many times before the school finally changed the policy.
I was at the school every single rainy day at lunch to make sure my girls did not go to the gym.
My daughters' teacher is no longer at that school, and neither are we.