When creating an activity, instructors have the option to hide specific content from students until after the activity due date, or after the activity has been graded.

To do this, once you add content to an activity, click on the options icon.

You'll see the options to always show the content, to show the content once the activity is closed, or to show the content once the activity is graded.

Once Closed means that the content will not be visible to the student until after the activity due date.

Once Graded means that the content will not be visible to the student until after the activity has been graded.

After you choose an option, click save activity. Your content will now be hidden from students until the specified time.