If you want to ski alot, at normal school you can still get plenty of skiing done. If you want even more, I wouldn't suggest online school because if you want to do any post-secondary it doesn't look too good. See if there is a good independent studies school in your area. Theres one in calgary called Bishop Carroll and basically how it works is you do school in packages at your own pace and check in once a week, then you do whatever you want the rest of the time. You can do all your school in the summer, and then ski in the winter, or finish school in a month if you can put in the effort. Thats what I want to do with a friend of mine next year, so I can ski alot and get the rest of the time off. Look into it, but make sure you have a few people on board with you to do it if you aren't doing a ski academy or whatever. It would suck if you were just going out skiing by yourself with no-one else. My mom finished high school early and said it was terrible because all her friends were still in school and she had nothing to do.
