Check out these online courses: Precalculus, Calculus One, and Single-Variable Calculus. Each is about three months (one semester) long, available on Coursera for FREE, and includes weekly video lessons, peer-interactions, testing and evaluation, and a certificate of completion. I'll tell you when I evaluate other sources of online course materials: udemy, edX, and so on.
If I was assigned to teach a large Calculus class, I would probably just reuse these resources as it would be hard to do better than some of the online courses I've tried. Even for a small class, I might embed this material, as in modularity, as in a course within a course.
|From Calculus Single Variable on Coursera|
For more elementary mathematics, like primary and secondary school (but also up to Calculus and hobby math), I like the quizzes at Khan Academy for math drill. Khan also has extremely, extremely good video lessons.