Looks really neat. I have lots of questions that I couldn't get answer on the site though ...

* What's the business model? Are they charging teachers / students / schools?

* Does it allow people to charge money for the classes they build? Or all classes are meant to be free?

* Would be nice to have a demo / way to see how easy it is to build classes, e.g. add content, create quizzes etc before having to sign up.

Otherwise, looks very promising.