I think this might be of particular interest to the K12 set:
"At the top of Speedgrader, it's easy to see what answers have not yet been corrected. However, if a student wants to see what he or she got WRONG, it's a slow scroll down the page, especially if they got only a couple wrong on of a large test.
I am suggesting that at the top of the page, you add a visual aid: red boxes (perhaps with an X through it) for questions that are incorrect. This would also be helpful if we wanted to give partial credit for something which may have been marked incorrect."