The Gradebook includes many aggregation methods that can be used to calculate students' grades. For each method, the grades are first converted to percentage values (this is called normalization) and then calculated using the selected method. Aggregation methods include:  Mean of grades
 Weighted mean of grades
 Simple weighted mean of grades
 Mean of grades (with extra credits)

Mean of grades: The sum of all grades divided by the total number of grades. 
Weighted mean of grades: Each grade item can be given a weight, which is then used to influence the importance of each item. Each grade is multiplied by its weight. The weighted grade totals are added together and then divided by the total of the weights. This determines the overall grade. 
Simple weighted mean of grades: The weight of a grade item is equal to the maximum number of points for that item. For example, a 100 point assignment has a weight of 100 and a 10 point assignment has a weight of 10. Each grade is multiplied by its weight (maximum number of points). The weighted grade totals are added together and then divided by the total of the weights (sum of all maximum point values. This determines the overall grade. 
Mean of grades (with extra credits): This is an old, now unsupported aggregation strategy provided here only for backward compatibility with old activities. We do not recommend use of this aggregation method.
