So the idea that a User can select which students and which day to view and complete the Roll Call must be flexible. But, if I understand, that does not mean it has to be created ahead of time (only DISPLAYED like it looks like it has been created). And that records only need to track absences and doesn't need to create an empty record for all the days when present.
When you view the example I presented, there are no records for the empty slots - only records for the red boxes. :-)
If you still need records for every single day then the script Comment suggested should do the trick nicely!! Otherwise just complete the sample display as I showed, use a global to display the span of time you wish to view and perform a find for the Students your User needs to work on.
I agree with Comment on your response, btw.