option to redo a test question w/o having to redo the entire test

I think it would be great if teachers could require students to redo a test question.   So in addition to the 100% 75% etc. there would also be a redo button.  Then a student could redo that question w/o having to retake the entire test.  Then when a student logged into his account, he would see the questions he has to redo just like we teachers see our "ungraded questions".