I'm going away this summer for the first time what do I pack?!?

I'm going away for 3 weeks this summer- I'm super excited, not nervous at all. The place is 3 hours away. The camp is on a boarding school campus and it'll be run just like a boarding school. Not really an outdoorsy-hike-through-the-woods-and-go-… sort of thing. There's classes, and sports, and dorm time, stuff like that. But here's the real question I have: WHAT do I pack? How many outfits? Do I have to take sheets or are they provided? My orientation is in a few days, but I want to get started early cuz I always rush everything. Could someone give me some tips on what to pack? It's being run just like a boarding school and plus there's a pool and a pond. And if it matters- i'm a girl and i'm 12. (: thnx