Does a Letter Grade Tell You Whether Students are Learning?

“If I memorize enough stuff, I can get a good grade.”
Joseph Barrell

What do grades tell you?  Colleges and Universities accept student in part based on their GPA, which is determined by their grades.  Students get excepted as transfers based on the grades they received.  A student’s ability to move on to the next course is dependent on grades.  One of the reasons schools created grades was because of transfers and advanced degrees. “Increasingly, reformers saw grades as tools for system-building rather than as pedagogical devices––a common language for communication about learning outcomes.”  A student’s transcript is a list of the courses they took with the grade they received.  Some employers even look at grades when hiring.

We could forgive society in thinking that grades tell us everything.  In a lot of ways, modern educational institutions seem to center around grades.  Even a lot of educational professionals believe grades tell us everything.  I once participated in a meeting where a school was trying to work out an assessment to prove that an educational intervention was effective.  After a little bit of discussion about some of the possible approaches we could use, one of the individuals that had not participated up to that point spoke up and said:

“All of this is incredibly stupid, a complete waste of time.  We know this technique works.  Anyone that complains is just stupid.  After all the students pass the course, and we have good student distributions.  What more does anyone need besides grades.” (Quote Intentionally not cited)

After this statement, several people in the meeting agreed.  Now there are a lot of issues with grades and GPAs. Leaving aside the issue of grade inflation, let’s ask the question, do grades tell us how much a student learns in a course?  Were letter grades even meant to determine how much a student learns over the length of a course?  Maybe grades were just meant to show what skills a student had mastered at the end of the course?  The last two questions may sound similar, but they are not.

Let’s start with what problems we can run into using grads to assess student learning.  Let’s begin with curved grads.  Faculty started curving grades based on the belief that student grads should match the normal distribution.  The bell curve began to take hold in the early part of the 20th century. “It is highly probable that ability, whether in high school or college, is distributed in the form of the probability curve.” (Finkelstein, Isidor Edward. The marking system in theory and practice. No. 10. Baltimore: Warwick & York, 1913. p79.)  If faculty use a curved grading system, then any variations or changes in student performance based on educational interventions will be covered up by the curved grades.

Outside of curved grades, there is also the fact that different faculty and different schools (if you work in a multi-school system) will often have different grading scales. There is also the argument that the modern grading system is not about teaching but sorting.  “All stratification systems require “a social structure that divides people into categories” (Massey 2007, p. 242). Educational systems are among the most critical such structures in contemporary societies.” (Categorical Inequality: Schools As Sorting Machines).

Suppose we could deal with all the above issues.  We use a fixed (none curved) grading system.  All faculty and schools use the same grading system and the same assessments.  We record all the data year after year.  Now if we introduce an educational innovation and a statistically significant number of students get higher grades.  Then can we use grades to determine student learning?

In short, No, if a higher percentage of students continue to get higher grades, you could say that you have found a better way to teach. You can’t say anything about how much students have learned.  Assessing how much students learn in a course requires a piece of information that the student’s grades don’t provide.

To determine how much a student or group of students learn throughout a course, you need to know what their starting point is.  No student is a blank slate when they start in a course.  While part of the job of an educator is helping the student identify and deal with miss conceptions, incorrect information brought into a class.  Students will also bring correct information into a course.  Suppose you assessed all your students at the beginning of your course and discovered that all the students that got As scored 90% or higher on your pre-assessment.  Did you teach you’re A student’s anything?

 Measuring how much a student learns over a course based on their starting and ending knowledge is called Learning Gains.  The critical thing about Learning Gains is that it is a measure of how much a student can learn.  As an example, your pre-test showed that student A already knows 20% of the material that you will cover in the course.  While Student B already knew 30% of the material.  That means to reach 100% student A needs to learn 80% while student B needs only to learn 70%.  The actual learning gain of a student can be calculated using the mean normalized gain (g), which is calculated by (post-test – pre-test) / (100% – pre-test) = g.

Therefor using pre and post-tests we can measure the actual amount of learning as a fraction of the total learning that can occur over the length of a course.  While grades are useful for a lot of things, they don’t tell us how much students learn throughout a course.  Remember when you’re trying to improve your teaching use a measure that will show you the information you need.

Thanks for Listing to My Musings
The Teaching Cyborg

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