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  How to grade using letters?

If you prefer letters to numbers, enable letter grading (A, B, C, etc.), go to Parameters > Other modules > Grading, check Activate and select the distribution mode:

• according to a distribution in decile of the class' results: you can click and drag the separators to modify the percentage of students obtaining such or such mention,
• according to an equivalence with the digital grades: enter the wanted grades in the table.