[robryan]

Guess it has a lot to do with having to be corrected automatically rather than a professor going through your process on questions with individual correction.

That might actually be an interesting AI research area, making computers better at marking based on process the student used rather than just the final answer. Wonder if much has been done in that area as it will become more important as more learning goes online and people want more than multiple choice/ final numerical answer type stuff.

[dhotson]

They can probably infer it based on the distribution of answers.

They can probably infer the mistakes people made by looking at the really common but incorrect answers. I'm guessing that lots of people get the same wrong answers as each other.