Have you ever accidentally overwrote a grade in your gradebook? Then check out the Mode pull-down available on the left side of the orange bar in your gradebook.
The default mode is Points. All grades are editable in this mode.
The next is Percent which shows all grades as a percentage. Grades are not editable in this mode.
Locked allows you to enter scores in blank cells but prevents you from overwriting grades already entered.
If you are looking to see the grades of your dropped students, click the Show Dropped button to the right of the Mode pull down menu.
