My son is taller than almost all his classmates, so he doesn't get bullied. And he can fight.
But I'm still on top of EVERYTHING. No matter how small it is. If he comes home and tells me a kid tripped him, yes I'm THAT parent that is calling the teacher the next day

I don't play about my kids. I don't let shyt slide when its about them. And if it really came down to it, I'd slap the shyt out of somebody's child and then tell them to go get their mother
People REALLY have to listen to their children. My son tells me his whole school day from arrival to dismissal. Everyday. I've seen some people brush their kids off when they are trying to talk to them. I don't do that. Even if its some normal, stupid lil kid shyt, I always listen.
Also, I know a lot of people have this "we don't run from our problems" mindset. But when you see your child is REALLY going through it, just pull them from the school. I know where I am, your child isn't only confined to the closest school. They can pretty much go to any school, especially under emergency circumstances like being bullied. If the school isn't taking your concerns seriously, pull your child and then sue their ass.