Node: Seeing past answers, Previous: See a student's version of a particular problem, Up: Keeping tabs on your students
Every problem page which comes up has a Show Past Answers
button
near the bottom. If you act as a particular student, then go to the
correct problem, that button will show the answers submitted by that
student on that problem.
Once you have the Show Past Answers page open, you can change the parameters to entries for all students on a given problem, or all submissions a single student made in a set. To change a item like problem number from a specific value to all, make it blank.
Note, only recorded submissions are shown. If a student previews an answer, or checks an answer after the due date, those are not recorded (and so not shown under Show Past Answers.