I've noticed that a lot of people have been asking for the best textbooks to buy for next year. Why pay money when you have the information at your fingertips? Check out these sites that high school teachers created for their students. This is not a complete list. These are sites that I am using, have used or would use if I was taking the class. There are a ton of more sites for you to find- just look. This took me a couple of hours to create, so please use these websites. I didn't put any for language classes, but you can easily find sites if you type in something like "AP French notes" on google. I hope this helps you. Many of these sites have helped me, and I feel selfish not spreading them around. Good luck and have fun.
NOTE: Some of these sites might change...especially since the end of the year is almost over and some teachers delete or take their notes offline. The majority of the teachers don't, though.