I have huge experiences with bullying, that resulted in me getting some very bad, addictive habits and all kinds of treatment, all because of how I was treated in school. I'm sad to say that I was bullied right into senior year, all the way from primary school - about 5 years. I had (still have, but to a lesser extent) a very severe stutter, which was found amusing, and I was rather heavy as a child, and even after "slimming down" I had (still have) a rather fat stomach, which was also tease worthy.
Here's a thread with my story - I'm going for treatment... Bullying. *Slightly long*
I put this up here, because my mom never really tried to stop what was happening. She tried to stop the RESULTS of the bullying, but not the bullying itself. I guess it had happened so many times for something (my stutter) I can't control that she lost hope in it ever stopping. After a long time of treatment, and the bullies actually, FINALLY being punished severly, and my state of mind recovered, things got better, and the latter half of my final year became the best of my school life.
You as mothers are doing a great thing, trying to put an end to bullying. I'm not saying your children will end up like me (I'm a very "complex" person apparently), but bullying can have serious results, so PLEASE keep trying to do it. Children (and teenagers) can be very cruel, without actually realising it, so they need to be made aware.