When reopening a new quiz attempt, it is not clear how much time remains to a student. I propose that the time that will be allowed to a student whose quiz is reopened be clearly displayed on the same menu as the reopen button.
Use Case 1:
Since transferring to new quizzes, I have had several students whose quiz needed to be reopened. In these cases, something interrupted the student's progress and the quiz was auto submitted once the time ran out. The main moderate screen displays that the student took the full time, whereas the log reveals how long they were actually working in the quiz.
I can now tell you that it is the quiz log time that determines how much time remains, but the first time I reopened such a quiz, I added the difference between the quiz log and the moderate tab display to the attempt - just to make sure the student would be allowed that time. The result was allowing the student double time. A simple note on the menu would have cleared that up, "if reopened this student will be allowed __ minutes that remain on this attempt." I would be happy with just: "time remaining: ____"
Use Case 2:
After I reopened a quiz, a student found that it would not work and I tried to help her troubleshoot. The reopened quiz ran through the remaining time with only a loading screen displayed. At the end of the time I waited on canvas support for hours, they diagnosed the problem (new quizzes is not backwards compatible after chrome updates), and so I could try again with the student. However, even canvas support could not accurately tell me how much additional time to offer the student.
Why? I had already added time to the attempt (due to use case 1.) Canvas support did not think the additional time had been used up yet, and told me the student had zero time remaining and so the additional time would be automatically added (added again, since I had reopened with that time added already.) Canvas support was wrong. The quiz reopened, but the student was immediately told she was out of time, and the quiz submitted.
Showing the time remaining on the same menu as an update-able field interacting with add time to this attempt would have clarified the answer to Use Case 2 easily.