I don't want my student to work on the assignment at home. Can I exempt and then re-add them later?

The short answer is yes, but their progress will not be saved.

If you exempt a student from an assignment, they will no longer be able to access it, and it will no longer be viewable on their Assignments page. Please note: You can re-add this student back onto the assignment at any time; however, as mentioned, any previous answers will not be saved and they will have to start the assignment from the beginning again. 

To exempt: 

1. Go to the Assignment Report (get there from the assignment page by clicking on the graph icon for that assignment; you can also get there from the assignment's Dashboard or Grading page).
2. Scroll to the bottom of the Assignment Report to the Incomplete Assignments list.
3. Use the checkboxes to select the students you want to exempt and click the Exempt from Assignment button.

To add these students back to the assignment, you can click the checkbox next to a student's name in the Exempted from Assignment list. Then, click Add to Assignment.