I'm sorry to hear that your son continues to be bullied.  It sounds like he's tried several ways to get away from it, but is still experiencing the same problems.  How frustrating it must be that the bullies continue to be allowed to behave the same way at school.  Have you taken your concerns higher up in administration?  If you feel like your concerns haven't been heard by the principal, it's always an option to speak with the school board or superintendant of schools.  It's also a good idea to have your son talk to the school counselor.  The counselor may have other ideas as to what has worked for other kids who have experienced bullying.  

Continue to encourage your child to ingnore the bullies at school and speak to the teachers when appropriate.  To help your child build self-esteem insist they are involed in activities outside of school where they will received positive praise.  Get them involved in a summer camp with kids that are interested in similar things such as music, art, or sports.  If you can help encourage your son to excel in things away from school they will be less likely to take their bully's words and actions to heart.  Remember to give lots of praise to your child.  Now more than ever, they need to be reminded that they are a good person that doesn't deserve to be treated badly.  Remember that you and your son are welcome to call our 24/7 crisis hotline to speak with one of our counselors.  Maybe it would help your son to speak to a counselor that talks to hundreds of kids that have been where he's at.  We can offer support and even share with him stories of other teens that have experienced bullying.

Boys Town National Hotline
1-800-448-3000