- lessons are presented based on what you already know (e.g. you can't choose to study a topic before you've demonstrated mastery of all topics it depends on)
- I pick the next lesson from a very small set (usually 5 options, sometimes fewer), so there's no wasting time choosing what to study next
- really great spaced repetition system that prevents forgetting
- focused on mastery
- good treatment of math
How it's different:
- doesn't cover elementary school topics
- lessons are text, not video
- paid, not free
- lessons are presented based on what you already know (e.g. you can't choose to study a topic before you've demonstrated mastery of all topics it depends on)
- I pick the next lesson from a very small set (usually 5 options, sometimes fewer), so there's no wasting time choosing what to study next
- really great spaced repetition system that prevents forgetting