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1) Go to your Quiz Settings
2) Change Grade > Attempts allowed to 2
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5) Once they have begun their second attempts, you can delete their first, prematurely closed, attempts in your quiz results. Be careful to make sure you delete the correct attempt!
You will be left with a single attempt per student that began where the original (closed) attempt left off.
This will also work if you need to do it for a subset of students. Instead Instead of changing Grade > Attempts to 2 for everyone, create user overrides for the students who need their attempts reopened.
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