How do I create an Assignment shell in an Assignment Group?
Assignment shells are placeholders for Assignments until you edit the Assignment details. You can create an Assignment shell on the Assignments index page. Assignment shells are saved as unpublished assignments.
Assignment shells can only be created as part of an assignment group. Learn how to add assignment groups.
Create Assignment Shell
In an Assignment Group header, click the Add icon.
Enter Assignment Shell Details
Set the Assignment type by selecting the type drop-down menu , enter the Assignment title in the Name field , click the Calendar icon to select a due date  or manually enter a due date, and enter the number of points for the assignment in the points field . Click the Save button .
Note: To edit the assignment details, click the More Options button .
View Course or Term Date Error
If you have set a date that is outside the course dates, the assignment will display an error message.
Correct the date and then save the assignment again.
Note: If the course does not include specified course start and end dates, Canvas validates the assignment against the term date set for the course.