You have to fuck him up bad. There's no other way. Walk up to him from behind, tap his shoulder and punch him straight in the jaw with an uppercut. If he doesn't drop keep punching. If he's down, get on him and break his jaw. If you can't fight don't let him get up because you'll get your ass kicked.
It's the only thing that works. If you don't fight back other normies looking to get status will join in and you'll have half the class bullying you in no time. I've seen it happen many times.
It worked for me in 2nd grade. This faggot normie kept talking shit and throwing erasers at me. One day I just got off my chair during class, turned around and hit the normalfag so hard he fell off his chair. He wanted to be friends afterwards because he's a bitch.
The teacher was a pushover and she did nothing and if you're wondering how I got away with it, all you need to know is that I live in the balkan region. Everything is fair game in the balkans.
Our school was basically like prison. If you don't defend yourself, you'll become easy prey for normies. Unfortunately in places like America if you fight back, you get expelled. Try to fight him outside school.