2. Then click the 3 dots in the upper right of the assignment tile.
3. Click the calendar icon to the right of the "Due date" field.
Changing the "Available Date" from its default (the day the class was created) to a date in the future will lock the assignment so students can't access it until the specified date you select. If you do not change the "Available Date" from the default, all assignments will be available to students at the start of the term.
4. Click to select a date. Then click "Done".
The time automatically associated with the chosen date will be 11:59 pm in the local time zone of the user.
5. Next to "When past due", adjust the dropdown to choose whether you'd like the assignment to remain available to students after the due date or if you would like to restrict access.
Restricting access will make it so students cannot rewatch content within an assignment after the due date, but will keep them from continuing test attempts (should they have any attempts left available per the class setting).