For each Subject:
When you enter numeric marking marks (using a numeric marking scenario) you basically enter numbers to several columns (i.e. to several numeric marking criteria used/defined in the numeric scenario).
E.g. Project, Essays, Writing. Those criteria may also have weights. When you enter e.g. 55%, 65%, 90% then Classter will calculate a Final Overall Grade as a weighted average of all these numbers. Then the end-user may be allowed to change the final number. This is saved in a column named Overall Grade (free). [Note: It is called free because it can be updated/changed by the end-user, i.e. by the teacher)
Many schools do not use the above structure, and they just need a final mark entered by a teacher per marking period. This is directly saved as an overall grade for each marking period. (Overall Grade Free).
Usually, schools using this approach want also to enter a set of descriptive criteria.
It is not user-friendly for a teacher to go firstly to descriptive marking form, enter all descriptive marks, write a descriptive assessment for the student and then enter again the normal numeric mark form just for entering an overall final mark.
Thus, we have enabled the descriptive scenario so that a teacher can enter all descriptive marks, write any text and then enter a number (final mark). This final mark is saved as an overall grade (free) in the selected marking period.