Mortarboard is a badge for earning 200 rep in a single day, much like Suffrage is a badge for voting 30 times in a single day.
Whereas the progress tracker for the Suffrage badge (is there a more official name for it?) counts up to 30 and resets at the end of each day, Mortarboard only counts up to 1. You've either gotten the badge, or you haven't, essentially.
I understand that for a few badges, there's really nothing more granular to count, either you've done something or you haven't, so only counting to 1 makes sense.
Mortarboard should show a progress bar of how much rep you've gotten today over 200, just like Suffrage shows how many times you've voted today over 30 or Vox Populi shows how many times you've voted today over 40.