Converting Scores to Grades
Scoring on a rubric is different than assigning a grade. When you score an assignment on a rubric, you are providing yourself and the student with specific information about how well the student’s work meets the course goals, and hence how well the course is achieving the goals set for it. When you grade an assignment, you are providing information about how the results of the assignment will affect the overall course grade. In multi-section courses, scoring needs to be consistent across sections; however, grading can differ between instructors.
Rubric scales are ordinal, that is, they rank order artifacts. Grades are actually ordinal as well; however many instructors think of grades in percentage terms, for example 90% and above is an A, 80% – 89% is a B, etc. If your grading scale is a percentage scale, then it can be a struggle at first to differentiate between the act of scoring and the act of grading. However, it is fairly easy to choose scale values and to weight the dimensions of a rubric so that you can convert the rubric score into a percentage score more typically used for grading. The benefit of this is that the feedback to students will be based on dimensions and criteria related to the course learning outcomes, while fitting into your overall course grading system.
To convert a rubric score to a percentage grade, you will need to assign points to each level of the scale, and you may need to weight the dimensions. The following is a simple example.
Level 1(12 – 16 points)
Level 2(17 – 22 points)
Level 3(23 – 25 points)
In a rubric with four dimensions, each dimension will count for 25% of the score (and grade), unless you weight one dimension more than the others. For this example, we will not weight any dimensions. With each dimension counting 25%, or 25 out of 100, the top score should be equal to 25, or at least 23 points (23*4 = 92). If you feel that Level 2 of the scale is worth between a B and a C, then the score for Level 2 should be between 17 and 22 points. The lowest level takes a little more thought, and the lowest score for that level will depend on how low you want to allow the score of a completed assignment to be. In this example, a student who was scored a level 2 in each dimension could receive a grade between 72 and 88.
The following is a more intricate example. In using this studio art rubric for an intermediate class assignment, the instructor has weighted Technique twice as much as the other dimensions, to reinforce the practice of the techniques being taught in the class.
Studio Art Assignment Rubric
|Expression||Work appears to have limited unique characteristics.||Work has some unique forms or composition, although in large part references previous work.||Work appears unique in its compositional arrangement, with little reference to previous work.||Work appears unique in its concept with no apparent reference to previous work or known cultural icons.|
|Technique (x2)||Work contains many errors, improper use of materials, little understanding of technique.||Student demonstrates a developing ability with material and technique, with a number of errors.||Student demonstrates a high level of success with material and technique. Few errors in completion.||Student demonstrates a mastery of materials and techniques.|
|Design||Parts of the composition appear disconnected, and a unified whole is not achieved.||Some elements of the work appear unified, although some disconnected elements distract from the visual order.||Work appears unified with few distractions in the visual order with regard to the elements and principles of design.||A professional level of unity is achieved with regard to composition.|
|Assignment Requirements||Student failed to address most of the assignment requirements.||Student did not satisfy some of the assignment requirements.||Student satisfied the assignment requirements.||Student completed the assignment requirements and made interesting personal contributions.|
In the example above, a student who scored a Developing in Expression, an Apprentice in Technique, a Developing in Design, and a Mastery in Assignment Parameters would receive a minimum score (and grade) of 14 + (16*2) + 14 + 18 = 78 and a maximum score of 15 + (17*2) + 15 + 20 = 84.
You may need to play with the points assigned to each level to represent your grading systems. And you can assign just one point value to each scale level. Weights for dimensions should be used to indicate the importance of the dimension relative to the overall course goals.
Last modified April 14, 2009