Dashboard > Manage Courses > Edit Course > Go to Course

Instructors can either leave the assignment open, or provide open/close dates.

1. From your course, select the module and assignment.
2. Click the gear icon and Edit settings.
3. Select the tab Timing.

Here you can change your open and close dates, times, and other settings.

Please note that the on/off switch next to each field must be set to on to make any changes.