An Algorithm for Assigning End-of-Semester Letter Grades

Assigning mandated end-of-semester letter grades to students is non-trivial. [1]  I refuse to constrain myself to a simple, cumulative percent score that automatically sets my students’ grades.  In my opinion, the accuracy as well as the precision implied in many quantitatively represented scores grossly misrepresents reality.  Furthermore, uncertainty abounds in assessments as in life.  Our role as educator requires a holistic approach to assessment.  No student is a number, and no number defines a student. [2]  Yet, chained to the perceived objectivity of quantitatively defined measures, teachers do their best to assign grades reflective of student mastery.

As an example, to honor my students’ efforts over the entire semester, I employ aspects of the following algorithm when determining their final grade.

Grading Algorithm - Single Slide

I say “aspects” as, depending upon the course or academic year, I alter the category weights and/or the inputs to the decision-making process where I select a maximum, overall percentage score.  Nonetheless, this diagram faithfully embodies the spirit of my end-of-course grading algorithm where I reward students for their content understanding and proficiency, even if it takes them the entirety of the semester to develop said understanding and proficiency.  This algorithm also accommodates the chaos ever present in a large collection of souls.

However, an unfortunate artifact of implementing this process with our district’s grade book software sets the stage for potential confusion.  When a student logs in to see their latest course grade, which is the subject of a future post, the software displays the overall arithmetic percentage it computes (see “in progress % score” in the figure) directly underneath the letter grade I assign, where the two may not align in my grading scale. [3] However, the letter grade never falls below its corresponding percentage score. [4]

Also, note that this process includes conditional logic, which most grade book software does not support, at least in a straightforward manner.  Hence, there is the need for a “human-in-the-loop,” which opens the door to cries of subjectivity.  Yet, with only one parental complaint and one separate, student complaint in nearly one thousand semester grades assigned to date, it seems to serve its design objectives quite nicely.  Both complaints arose last semester regarding my honors precalculus course.  [5, 6]

What process do you use to assign letter grades to your students?  Does your district permit the use of standards-based grading without requiring the use of letter grades?  How subjective are you in assigning final letter grades?  Does the use of an online portal to your grade book that is accessible by students and parents alike help or harm assessment and/or student efforts?  How long does it take you to assign a letter grade per student?


[1] My grading preference strays far from the traditional use of A through F letter grades to that of standards-based grading with its richer, more meaningful representation of student mastery learning.  However, my district utilizes a letter grade scale constraining my ideals.

[2] Unfortunately, in the name of objectivity, efficiency, and for a host of other reasons, a quantitative scale, interpreted as sacrosanct, too often solely defines student self-efficacy thereby overly influencing his/her future outcomes.  The fidelity and/or validity of the scale, measure, or data are rarely questioned.

[3] While I must assign letter grades, I have the freedom to define the relationship between a percentage score range and a letter grade. In so doing, I replace the district’s traditional ten-percentage points per letter grade scale with my own fifteen-percentage point scale, as shown below.

Grade Scale

I input the first two columns into the grade book software as a lookup table representing a teacher-defined grading scale.

[4] Last semester, informational dissonance from this misalignment descended upon three-fourths of the students in my three honors precalculus courses.  To offset its effect, I notified students via an explanatory email.

[5] One parent this past semester expressed extreme displeasure with the “subjectivity” implied in my grading algorithm where I allow myself to bump a student up to the next letter grade designation if they are within three percentage points of a cut score, which may simply be from a C- to a C, as an example, with no impact on the student’s GPA.  The parent went so far as to complain to my administration presenting a double-bind scenario where I might discriminate against his/her child by misapplying my process.  This person seemingly places their full faith and trust in a computed number, irrespective of the subjectivity inherent in scoring individual assignments, over that of the professional judgement of a teacher.

[6] Only one student complained about their grade.  However, his/her issue was not the misalignment per se.  As they retook the course solely to improve their grade point average, and unfortunately scored at a similar letter grade range (“-” to “+”) they wanted me to bump them up to the next highest letter grade.  I refused since in the process of assigning their final grade, I discounted their assignment score, which would have brought their “in-progress” / grade book computed percent score to a lower score than I assigned.


About Dave aka Mr. Math Teacher

Secondary math teacher teaching math intervention, algebra 1, honors precalculus, and AP Calculus AB. I spent 25 years in high tech in engineering, marketing, sales and business development roles in the satellite communications, GPS, semiconductor, and wireless industries. I am awed by the potential in our nation's youth and I hope to instill in them the passion to improve our world at local, state, national, and global levels.
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2 Responses to An Algorithm for Assigning End-of-Semester Letter Grades

  1. Dave your senior ( experience and age only) says:

    pass/Fail/Honors would be best in theory. Instead, give students categories and weights. Have them assign and justify. provide source info to them. Most will under value. I did this once wo providing any data. Worked out well but it was an honors class.


  2. gflint says:

    I am so glad we no longer do letter grades. Grades are just the percent for the class.


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