It's all about balance. Remember if you really want to do well in both school and gymnastics you will find a way to make it work.
Here's what I do.
Any free time I have I use to get a bit of homework done. An extra 10 mins here and there really adds up and makes a difference.
I catch the bus, so I use this time to read through any of my notes and with a bit of practice I'm even able to write on the bus (although writing my Japanese homework on the bus is a little hard, so I leave that for home).
I always have some homework packed in the car so if I get to the gym early, I can get some more done even if it's only 10 or so minutes.
If you finish your work early in class then start your homework in class.
Try and get to school a bit early so you can do some work before class starts.
You could also use some of your lunchtime to do homework, you don't have to do this everyday but maybe one or two lunchtimes a week eg. every Wednesday you could go to the library and do homework, that way it becomes a routine and your friends just except that that's what you do on Wednesdays.
Also you and your parents could talk to your teachers about balancing school with gymnastics to see if they could give you extensions or a bit less work. Maybe you could go to less P.E. (sport) lessons and use those lessons to get your homework done as you're already doing lots of exercise with gymnastics.
Don't worry we've all gone through times when we've found it difficult to balance school and gymnastics but as long as you put the effort in you will find a way to make it all work for you.
Good luck
