Group wall post by Lizzy Bringhurst

I've got a kid in my class who instigates bullying. I think it starts off as friendly teasing, since he's an overly competitive person, but when others join in I think he gets carried away and comes off as really mean. They tend to gang up on one particular student, and I'm not sure how to intervene besides just asking them to stop or guilt tripping them. I don't want to take sides, either, because the student getting picked on will often say snappy things back. I don't have kids or siblings, so this is completely new territory for me. Help?
I'm no expert either but you gotta put an end to it. Maybe talking to him privately. Although I would, and I think I need to do this too for a different reason, go over class rules or guidelines again... it's mid-year and maybe they need a reminder. Everybody should feel safe in your class. Everybody should be trying to invite the spirit. Bullies were probably at one time the victim so he might be exerting power and cruelty because he's found somebody he can control like he's been controlled. My own children have been the victims of being bullied at church and it's something that should not be tolerated.
Thank you. I talked to them once about it before and it worked for a while, but I guess it's time again. I also don't want to embarrass the kid being picked on by drawing the attention of the whole class to it, so I think talking to the instigator privately will be my first step. It's difficult when it's that subtle kind of bullying that rivals on friendly competitiveness/personal attacks.