How can I quickly see who wasn't in school on a certain date?

The easiest way to see this is to go to Not In School. 

 Register > Not in School. 

Choose which date you want to view, and use the other filter options as needed, then click choose.

This will now show you who was not in school on that date, as well as any students who were not registered. 

 Please note you can click on codes in here to be taken to the Manage Register area to amend if needed