We used the Art of Problem Solving (AOPS) online classes to provide our child courses outside the normal path (Number Theory, Counting and Probability), and it was a very good program. Doing this in middle school around Algebra II time left the high level math courses through Calculus in most of high school to have peers, and those classes were easier compared to peers due to the rigorous foundation of the AOPS classes.
We used the Art of Problem Solving (AOPS) online classes to provide our child courses outside the normal path (Number Theory, Counting and Probability), and it was a very good program. Doing this in middle school around Algebra II time left the high level math courses through Calculus in most of high school to have peers, and those classes were easier compared to peers due to the rigorous foundation of the AOPS classes.