[tzs]

I don't think it is anywhere near 100k students. I can't find the cite, but I thought they commented somewhere that 20k or something like that people took the midterm.

I presume people are guessing how they are doing by just looking at their homework and midterm scores so far, weighted according to the appropriate weights.

[token4]

I think I saw somewhere that 100k+ students had signed up initially. However, according to this NYTimes article (http://www.nytimes.com/2011/12/05/technology/khan-academy-bl...):

"But in education circles, Mr. Khan’s efforts have captured imaginations and spawned imitators. Two Stanford professors have drawn on his model to offer a free online artificial intelligence class. Thirty-four thousand people are now taking the course, and many more have signed up."

Not sure if "taking the course" means advanced track and completed midterm or not.