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There are two cases for points based calculations, but the distinctions between the two are very slight. Whenever the 'organization' of the gradebook is set to "No Categories" or "Categories", points-based calculations will be used, independent of whether the "grade type" is set to "pointspoe ints" or "percentages". In setting up the gradebook, an instructor must provide a maximum number of points per item, or if one is not entered, a default value of 100 will be used.
So, in "No Categories" mode, we might create the following gradebook:
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This gradebook would have a total possible non-extra-credit point value of 100, with 10 extra credit points possible.
Each student's course grade is then calculated according to the point value (or in percentages mode, the percent of max points) assigned by the instructor, as per the following equation:
S = sum of all non-extra-credit points earned
E = sum of all extra-credit points earned
P = sum of all non-extra-credit points possible
% score = (S+E)/P
Of course when we include the ability of instructors to excuse an individual student from an individual item, we discover that P can vary on a student-by-student basis, as shown below:
Student | Item 1 | Item 2 | Item 3 | Item 4 | Extra Credit Item | S | E | P | % score |
|---|---|---|---|---|---|---|---|---|---|
Joe | 20 | 20 | 20 | excused | 10 | 60 | 10 | 75 | (60+10)/75 = 93.33% |
Melody | 20 | 20 | 20 | 20 | 10 | 80 | 10 | 100 | (80+10)/100 = 90.00% |
Note that in this case "Joe" gets more of a boost from his 10 point extra credit item than Melody does, simply by virtue of having been excused from one item . . . this is logical, since 10/75 (0.133) is larger than 10/100 (0.100), but it may be unintuitive at first glance to some instructors.