Calculating from conditionally formatted values

Aye up people, I've been tasked with writing a school database to replace the software which we currrently use to track students' grades. Belt-tightening and all... My biggest issue really is making it as user friendly for a variety of teachers whom will need something that isn't slower to use than say, writing the grade in their markbooks with a... quill...
I currently have rows for each student and in each column is entered a number of marks. The columns use conditional formatting to convert the mark into a grade. The head of department wants all the grades to be averaged at the end of the row. In short, is there a way to have the function take the value displayed in the cell, and not the data that was entered originally?
The long of it, there are various assessments with different values meaning, simply taking a percentage across all data won't work as the total could be anything. New columns could be added by any teacher at any time to record any grade they give throughout the year, so having a 'mark' column and 'grade' column which draws from the marks would mean I'd have to copy the function for them each and everytime - and I'd have to define which columns the average grade is referencing instead of just the whole row. Hidden columns, or a second sheet in which the data is entered would make it awkward for other teachers to use but without a solution is the most likely way forward.

Thanks all,
OLC

Great, thanks for taking a look. Column BA should average the contents across the row, which it is doing. But conditional formatting is taking the entered value and returning this as a grade (1-4) which is not the value currently being averaged. I want BA to average the grade as defined by conditional formatting and not the number inputted into the cell.
I hope you've got some thoughts.
Cheers,
OLC