My grades are slightly falling down! Help?

My schoolwork has always been really good, and I always used to be top of the class for everything, but now I never seem to be able to concentrate, and there are some subjects where I'm clearly not top of the class!
I have been called a geek in the past, and worse names than that which mean pretty much the same. Maybe this has something to do with it?

I really don't know why and I would like to do something about it to get me higher grades again. Any ideas why???
Thanks for any help!! I will vote a best answer soon. I'm 12 by the way

First, try not to panic about it. That'll make it harder to work with the issue.

For the classes where you are having more trouble. Talk to your teachers. See what they think you should try to do differently. Ask for suggestions and study tips.

Also, think about your lifestyle. Are you getting enough sleep? Are you eating properly? Do you have situations with your friends that are distracting you in class? Are you spending enough time on school work? Are you getting enough down time to let your mind relax some? Are extracurriculars or your social life taking to much time? Distractions with boys can take your focus away from your work because your feelings can go all over the place and that makes it difficult to concentrate. Your parents can help you think about these things and figure out other things to try.

Remember... no one is perfect, and no one is perfect all of the time. You're still young enough that this won't impact your college options, so you've got some time to work it out. :-)

Puberty. It does weird things. Just weather the storm and understand that when the dust settles you will be fine. It's just your brain changing as you grow older.