Yea, I was all of 10 when the neighborhood kids of 12 (who were up in badass Jr. High) "showed me what to do."
But that's a different thing.
But this case sounds like classroom bullies beating up on a smaller classmate who they didn't like. In that respect, is it really "sexual abuse", or just bullies being bullies. When I was that age you'd be called a cry-baby for telling on bullies. You were told to fight back.