When I was 10, I had to face the school bully in the Gymnastic changing room. He went whipping the minors (everyone was scared of him) with a wet towel (most being half naked).
I ended up trying to stop him, so he went for me. I used a thick leather belt from my trousers against his wet towel.
He ended up weeping on the floor, with red stripes all over
The guy was after me for the next year or so, but never caught me, - I could run faster, and just about everybody would always "accidentally" be in his way.
The moral of the story is that the group moral is VERY important, and to guide it, the teachers have to be quite good. They must have respect.
BTW, we became good friends later