I've been "bullied" before. Mostly through words, jerks don't want to fight. 6th grade too.
Specifcally, they had said "Happy Birthday" when I had told them the day before it was NOT my birthday and WOULD NOT be until February 2nd. You can guess what happened. They kept at it, I kept telling them, and eventually, it blew off my top. I lashed out in pure rage and they still messed with me. So I got the principals in to help. (by the way. school I go to has 3, one for each grade) They stopped...for a while. Soon enough School had become punishment for me, I had to make sure I was either with my friends or in the Library (our librarian at the time was very good friends with me, she;s in a different school now though) or even in a classroom doing work. For someone with a mental disorder, that can be pretty hard on you. Especially since none of my parents would get home until at least 4:00 PM. I loathed the school days. I couldn't enjoy my time there. I was seriously thinking of doing something...physically harmful (ie:intentionally breaking a bone, hurting self, etc.) until Summer Break came out. Never had that problem again, until this year, 8th grade. Some other jerks started the same problem up. But that has been taken care of.
So in retrospect, deal with things swiftly. Don't let them know what you're doing. If they know, they'll avoid the authorities. Do things quickly.
One of my friends in 6th grade was annoying me. Now, in 8th grade since he knows my anger, he tries to keep others from annoying me. Amazing how sometimes when a bullying happens it might end up in your favor, and then some.
EDIT! After reading through some posts here, I agree on what bullies are. They're just people that pretend to be the boss. Most of the time they don't know that inside that anger goes up and up and up. And eventually, they get it. And pretty bad too. Reality is, most bullies don't think into the future. Some people, like me, will remember what they did. So if they try to work for you, I'll make sure that they do work for me, but they'll get the worst jobs, and I'll make sure that they're life is living h***. If they complain to me, I'll make them remember what happened. This is your punishment. You don't deserve a life with benefits and other fun stuff. I will make sure that you experience the h*** I was through to show you what happened to me. I'll make sure that any job you get will involve living h***.