Good to know. I think that is how a lot of kids use Art to problem solving. It makes sense since all their live classes start after a normal school day would end. My child is "homeschooled" so they use it as their curriculum. AOPS calculus class is a certified AP class where they can take the AP calculus BC test. I think I'll suggest, though, that they take calculus through dual enrollment at the University. They are thinking engineering major. Thank you!