We were recently in a similar situation and had to go to the teacher to deal with it. DS's teacher said that the other boy was just trying to be friends with DS but he didn't know how to make friends nicely, so resorted to hitting and in our case, pulling people off the back of ladders on the playstructure. DS was dealing strictly with physical bullying though, no words or taunts. I actually felt his teacher went too far the other directions- banning both boys from being near or speaking to each other at school, unless in her room supervised.
She did suggest in some ways that DS had "asked for it" by being the smartest in class and told me that we'll have to find a way to teach him to deal with it. I hated hearing that but at the same time, it needed to be said. This is likely not a one time situation and we have to step up and teach DS how to advocate for himself.
Our school has a no tolerance policy for violence. If any child hits, even in defense, they are supposed to be suspended. So we've gone a different route and practiced at home. He has 3 steps- 1) ask the child to stop 2) scream and make a scene- STOP TOUCHING ME RIGHT NOW 3) Get an adult- not a whine, not a tattle but "We need an adult to help resolve ____"
It's worked much better. He is getting more confident and isn't just taking it anymore.
