**sympathy**
My grandmother still treats me like a child. She turns 93 next week - everyone else in the family IS at least a generation younger than she is. She is the sole survivor of her siblings and grandpa's siblings as well.
Fortunately, she does give me more slack at 49 than she did at 9, 19, or even 29.........but she still worries about me driving for hours to come visit her or to head home after a visit. It is a grandma thing.............
In your shoes, I would try to find a cousin, an aunt (does your mother or dad have a "baby sister" who isn't that much older than you?), or a neighbor who could be trusted to stay over with you.
If it comes down to grandma or being taken out of school for four days to go with the folks - take grandma but have WRITTEN rules worked out between your parents, grandma, and you. You have permission to go to the library to study, stay after school for club meetings or band practise, and you can get a list of shows that you can watch (or a short list of shows & movies that you CAN'T watch - whichever might be easier to deal with). If it isn't on the list of forbidden shows (either by title or by genre - sounds like HORROR shows wouldn't be a good idea) - then the only thing grandma can do is ask if you'd watch something else that she might like (understand) better.
Perhaps four nights of watching "classic movies" with grandma while the VCR or TIVO records the shows that you would usually watch would be a compromise? Just make sure that grandma doesn't realize that the VCR in the "other room" is taping shows for another night.
Then see about renting a nice Rogers & Hammerstein musical, a Ginger Rogers & Fred Astair dance movie, or perhaps a Doris Day & Rock Hudson movie to watch - Seven Brides for Seven Brothers has great dance sequences......... Or ask Grandma for a list of her favorite movies - then pick three or four that you could watch together - especially if you could get the original - then a remake so that you two can "compare and contrast" the good and bad points of each movie. If nothing else - it will give her something to complain about besides YOU!
I can hear it now "Buddy Ebsen was much better in the tv series than this guy is in the movie remake of the Beverly Hillbillies and the OLD Duke boys were much cuter and their car was faster, too! Make popcorn, serve Grandma a soda without caffiene (so she won't be kept up past her bedtime), and order in pizza at least one night.
Ask about a girlfriend spending the night one night - so that the two of you can "study"..........perhaps a movie that the two of you have to watch for Language Arts or Drama class...........Romeo & Juliet, The Scarlet Letter, or Gone With The Wind...........
Can you check with a teacher about getting extra credit for history or language arts by interviewing Grandma about her memories - then spend a night or two doing that - then spend one more night "typing it up" so that she can read it before she goes home "for accuracy"? The last two nights you'd be busy typing, then she reads during the day, and you spend the last night typing in the corrections...........
And after two nights of being interviewed - Grandma could hardly complain that you were ignoring her.......