Pamela from KA here. We're using the same client-side SQL solution as sqlteaching.com (which is great!). Our editing environment is here and open source: https://github.com/Khan/live-editor
It's a lot of work to create the classroom management itself (that's done by a whole separate team at KA) so it's not something most folks tack on to teaching sites.
KA does have classroom tools and progress reports, but we don't have the ability for teachers to create their own lessons (if that's what you're looking for). More details on that here: https://www.khanacademy.org/coach-res/reference-for-coaches/...
It's a lot of work to create the classroom management itself (that's done by a whole separate team at KA) so it's not something most folks tack on to teaching sites.