0-Based Grading Concepts
For some courses, 0-based grading can better help students understand how their performance on assignments impacts their grade and can improve motivation, when compared with tradition al %-based grading. Some concepts that are useful in %-based grading do not transfer to 0-based grading, but a similar affect can be achieved. Examples of this are described below.
Giving Extra Credit
The goal of extra credit is to make it easier for students to achieve a higher grade by doing some kind of assignment or other behavior.
In %-based grading, teachers can help students improve their grade by giving them an assignment for points, but not counting that assignment the same as other assignments when the calculation for the final grade. For example, if a course had 10 assignments, each worth 10 points, for a total of 100 points, and a student earned 8 points on each assignment, for a total of 80 points, then the final grade would be computed as follows: sum of points earned (80), divided by sum of points possible (100) = .8 or 80%. If a teacher wanted to give extra credit, they could add another assignment, but not include it in the sum of points possible, but they would include it in the sum of points earned. For example, if the teacher added a 10 point extra credit assignment and the student earned another 8 points, the result would be sum of points earned (88), divided by sum of points possible (100) = .88 or 88%. The extra credit assignment would improve the student's grade.
Notice that in %-based grading all of the calculations depend on calculating the final grade as points earned as a percent of points possible. These calculations will not work in 0-based grading. In 0-based grading, students start at 0 points and their grade is based on a points scale, not a percent. For example, if the max points in the class is 100, the scale might be that a student earns an A grade when they have earned 94 points, a B grade when they earn 84 points, and a C grade when they earn 74 points. A teacher could reproduce the effect of extra credit in a 0-based grading course by simply adding another assignment to the course without changing the the max points in the class. For example if a course had 100 points possible, and the max points on the scale is 100, then a teacher could make it easer for students to achieve a higher grade by adding another assignment worth 10 points and not changing the max points value (100). Now students can do the extra assignment and those points would move them higher up the scale than otherwise would be possible, allowing them to improve their grade.
Dropping an Assignment
In %-based grading, another way to help students to improve their grade is to drop an assignment and not include it in the calculation for the final grade. In this case, you are changing the grade calculation by removing a grade from both the sum of points earned and sum of points possible before calculating the final grade. Typically a low grade is dropped and the result increases the calculated percent. For example, there were 10 assignments, each worth 10 points, and a student earned 10 points on 8 of the assignments and 0 points on 2 of the assignment, then the grade would be calculated as follows: sum of points earned (80) divided by sum of points possible (100) = .8 or 80%. If the teacher chose to drop the lowest assignment, the result would be as follows: sum of points earned (80) divided by sum of points possible (90) = .889 or 88.9%. Dropping an assignment would improve this student's grade. It is important to note that this would not help students who did well on all the assignments and may encourage students to intentionally do poorly on some assignments that they know will not affect their grade. This side effect of dropping an assignment is rarely desirable.
Again, notice that in %-based grading all of the calculations depend on calculating the final grade as points earned as a percent of points possible. These calculations will not work in 0-based grading. In fact, dropping a score will hurt all students because it will be harder to move higher on the points-based grading scale. In 0-based grading, students start at 0 points and their grade is based on a points scale, not a percent. For example, if the max points in the class is 100, the scale might be that a student earns an A grade when they have earned 94 points, a B grade when they earn 84 points, and a C grade when they earn 74 points. A teacher could reproduce the effect of dropping an assignment in a 0-based grading course by simply lowering the max points for the scale used to calculate grades. For example, instead of using the grading scale with a max-point of 100 described above, a teacher could change the max point value to 90. Now a student earns an A grade when they have earned 84 points, a B grade when they earn 75 points, and a C grade when they earn 66 points. In this scenario, all points count still and good students are not penalized for doing extra high-quality work. At the same time, it is now easier for all students to earn a higher grade.