I will pray for your son that when school starts this mean child will not do this to your son again. I get so upset when I hear of this, I have 3 children and they range in ages from 13 to 10 and then the little one 3. My daughter who is 13 would never tolerate it, when we moved 3 years ago she had a few girls who were bothering her at her new school and I told her not to put up with it cuz I knew it would continue if she let them, so she started to talk back to them and luckily it never had to go any further!! My 10 year old would be the sweet one who would take anything and I try to tell him not to let other kids who are not nice to push him around, he is little for his age so I worry. I think he is getting a backbone though. I do not tell the kids that is ok to fight but I do tell them that if a kids hit them that I give permission to hit back. My husband doesn't really agree with this but I think in today's world kids have to stick up for themsleves, if telling the teacher doesn't work then what else can you do?? Parents of bullies are to blame, I feel like they are ok with there kids being like that and ignore it also. Bottom line I can't stand bullies and I would be freaking out if I was you...
Good Luck!!!!