As a facilitator, you can re-open a file upload assessment for a learner if you wish to provide an opportunity for re-submission.
To do this, simply click on the re-open assignment submission button at the bottom of their assessment submission. Clicking this will remove the current submission, and allow for a new file to be uploaded.
Learners have the ability to submit assessments at any point during the course. The submission does not close so therefore does not stop overdue submissions. However, any overdue submissions are flagged with a time-stamp, which makes it visible to facilitators that the assessment was submitted after the expected date. How overdue assessments are handled is up to the organisation and/or the facilitator of the course.
Quiz extensions for an individual learner for assessed quizzes are managed on the Marking menu by a Facilitator. To do this, simply click on the learner's quiz icon and select Grant extension. Once you've selected a new date from the date selector, save your changes and the extension is granted.