@JohnKern @gnoack
I just looked through the document that I referenced. I think it will work depending on when the students are allowed to take the exam again and how long they have to take it. Make the late penalty 1 day and 20% per day. According to the example in the document, the 20% penalty is calculated as 20% of the max score (i.e 80 would be the maximum if the test is worth 100) - Canvas calculates the grade for the test and then the 20% value is subtracted from it. see the screenshot below which applies a 10% penalty for each day late:

For this case, I think it boils down to what is the time frame for students who need to take the exam again.
Based on what John wrote, it sounds like they could very well set up an exam with a due date of Monday at 10pm and an until date of Tuesday @10pm. Then at 10pm on Monday they go in and add the 1 extra attempt for everystudent who needs to retake the quiz. Canvas rounds up the late time, so a policy of 20% for 1 day means an exam submitted at 10:10pm on Monday night would be counted as 1 day late and therefore incur the 20% penalty.
The instructors could try this out in a sandbox by putting a couple of instructors in to it as students and setting up a quiz with times where they could check it out to see if it works to their liking.
This discussion post is outdated and has been archived. Please use the Community question forums and official documentation for the most current and accurate information.