Assigning Assignments

Kiera, so glad that you are using Khan Academy to provide support to your students. 

Yes, you may assign students the lessons by date/time. If you go under Assignments, then Manage, then Edit (since you mentioned you already assigned the content) you can then edit the date and time you would like the assignments to be due. Students would then need to be instructed by you of the order they are to complete the assignments.

You can also see this article for additional support:

https://khanacademy.zendesk.com/hc/en-us/articles/360031121631-How-do-I-edit-copy-and-delete-assignments-