Just found this free site, and it looks good. It looks as good as some of the commercial sites. Unizor
Its got a login for parents who want to supervise education of their kids, and it apparently has some way for them to supervise and for students to take tests that are then scored.
I'd say the teaching is about on par with Khan academy. So while it's very nice for these folks to do education for free like this, it's only so-so teaching quality.
So, mixed review from me: It's very generous of Zor to spend his time this way, but the teaching quality itself is not outstanding.