Students all want the same thing: status, popularity, etc. Not everyone can these things though. Their scarcity is their value. The competition over this finite resource creates conflict and hostility. This pent up hostility has to be channeled to avoid chaos. A scapegoat is informally agreed upon: the oddball, the misfit, the outcast. These people are all the more obvious due to the extreme herding that happens in schools. The bully acts as the "executioner" of this "sacrifice". The boundaries of group unity are enforced, the shared complicity enforcing cohesion, and group identity and control are upheld.

I remember from my school days how much hostility was directed toward people who wouldn't or couldn't "fit in". I even internalized those feelings. "Why won't he/she just act normal?"

I'm not fully sold on Gerard, but his theories are kind of mesmerizing in their pat explanation of group dynamics.