If you would like to allow a student to retake a quiz that s/he has already received a score on, you can do so by clearing that student's existing score on the quiz.
- Select Classes on the top blue bar.
- Click on the name of the class for which you would like to allow a student to retake a quiz.
- Select Quizzes on the left sidebar.
- Click the name of a quiz.
- To the right of the student's name, click Clear.
- In the pop-up window, click OK to permanently remove the student's score on the quiz.
Please note: In order for a student to retake a quiz, his/her score must first be cleared (by following the steps above) and the quiz must be Open.