You can do schoolwork at your own pace, without the distractions from other students. You can sometimes (depending on what online school you're considering) customize your school to fit you better, play at your strengths and work on your weakness. If you have trouble at math, than you can spend extra time there, or if you're great at english, you could spend less time working on that, while in a regular school you have to work in the time that the teacher gives you.