It is bullying if its hurting him emotionally or physically, some kids could brush it off, others can't.

Agree that his best tactic is ignoring them, let them know it doesn't bother him what they think of him, build up his confidence and whatever you think of whats going on support his feelings about it all so he knows your on his side 100%. Words can be extremely powerful, say something often enough and it sticks. An interesting fact for you: for every one bad thing a person hears about themselves it takes 7 good things to undo the damage...something you can make very good use of in this situation. My daughter had a blackboard on the kitchen wall when she was being bullied in this way and we'd keep a list of 7 positive things about her on it changing it regularly...very effective. Try and get him to join clubs out of school, martial arts for example build confidence and self esteem and he won't be the only one going due to bullying problems so he may find he just slots in better with the kids there.

I love the advice you got so far, especially the chart, you can even keep it in a more private spot in your home, if you think your son (being a bit older) may be embarassed by it. And telling the school without your child knowing is brilliant.

When my kids come home and talk about the bullying they witness at school, we talk about the bully and try and figure out what could be bothering him. What are the hardships in his life that he's not able to cope with properly? My kids understand that a bully is not a bully, but a child hurting inside, and often if you could figure out what might be hurting that kid, you can help 2 at once, yours most importantly, but the bully too, and in turn the other kids that the bully won't move onto if he/she learns a better way of dealing with their feelings than hurting other kids. I would demand the school deal with the bully with counsel, not punishment, and your childs ease at school should follow. A child who is told that an anonymous person is concerned about them has to wonder who that is, but enjoys the idea that someone they may not even know out there really cares. I remeber having that feeling once myself. Your child may be past the point of understanding the kids hurting him, but if he can learn to understand, sympathy is a much better feeling to have than anger, which your son seems to be avoiding well already. Please keep us posted, I'm always most concerned about the bullied kids, they can be pushed to unbelievable limits and don't deserve to dread waking up and going to school every day. I've been there. What a strong boy you have.

My advice may not be the best for older kids like yours, but it works well with mine. Good luck, your doing great!