Instructors have the ability to make an assignment extra credit by following the instructions below:
In the Administration block, Click on Grades, then click Setup and choose Categories and Items

Locate the assignment and click on Edit then Edit Settings.

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Locate the Parent category area, check the Extra credit box and click on Save changes.

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Notice that now in the Categories and items area, a ‘+’ will appear in the ‘Max grade’ column for an extra credit assignment.

Note: When the extra credit checkbox is ticked, the grade item’s maximum grade is not added to the category’s maximum grade, resulting in the possibility of achieving the maximum grade in the category without having the maximum grade in all the grade items.