Guest Column

Toll the Death Knell for Bell Curves

by Judy Willis

Looking out at the attentive faces during math class, I recalled these same students several months before.

They were looking out the window, playing with coins in their pockets, doodling in their notebooks or talking to tablemates about anything but mathematics. About half of these middle school students started the school year in my class math phobic, frustrated or bored. The average scores and mastery on their first tests were about a C-plus. A graph of their grades at the time might have resembled a bell curve.

After I began offering opportunities to do detailed test correction papers and take retests to demonstrate what they learned, these students became interested in math, worked harder and grew in skill. By the spring term the lowest grade on any test was a B-plus, and standardized test scores matched the improved classroom grades. That was when an administrator imposed a harsh new rule on grading, and I had no choice but to leave that school.

Assessment is a necessary part of education, especially when formative feedback improves the quality of student performance and teacher instruction. However, bell-curved testing and course-grading systems tend to reduce motivation and increase student stress and alienation from school.

Students now more than ever need to feel some sense of control of their academic success, that they are more than numbers on a curve. Eliminating requisite bell-curve grading that opens up A and B grades to all students who achieve higher than 80 percent mastery of the material can to be a positive incentive for effort and achievement.

Building Confidence
As a neurologist and classroom teacher, emotional well-being and self-confidence are valuable for cognition. Data from recent brain research using neuro-imaging studies indicate greater activity in the higher cognitive prefrontal regions during low-stress, high-engagement learning experiences and more brain activity in the automatic, reflex behavior networks when subjects are anxious. Support from cognitive evaluations associates better long-term memory of information learned during low-stress, high-engagement neurological states. The successful translation of sensory input to knowledge and long-term memory is contingent upon many factors, and the stress response is one we can influence by reducing unnecessary classroom stress such as bell-curved grading.

Students build confidence when they achieve goals they value and their effort is recognized as they make progress toward these goals. Students do not have fully developed delayed-gratification skills during their school years. The neuro-logical basis of this appears related to the fact that the last part of the brain to mature are the prefrontal lobe networks involved in executive function, reasoning, delayed gratification and goal setting. Students from kindergarten through high school need support and encouragement from their teachers to keep their efforts directed on long-term goal achievement.

Judging Students
Students are motivated when they value the goals they can achieve and consider them within their reach if they extend the effort that they understand will result in success. The bell curve does not allow for more than half of the students to receive grades indicative of success regardless of their knowledge and test scores. The bell-curve model of grading limits the number of students who can be recognized for above-average mastery because the more the class achieves, the higher the average mastery on graded tests becomes and the more the apex of the bell shifts to the right. Classwide achievement has a negative impact on tests scored on a bell curve. If the grade range is 80 to 100 percent, 100 becomes an A and 80 becomes a D. The bell-curve system fails to provide that encouragement or positive reinforcement for students’ steady efforts and mastery when all students achieve success.

A longitudinal study of middle schoolers noted that teachers who emphasize competitive comparisons of student ability discourage students from asking for help. With competitive grading, the bell curve compares students to each other, not to the level of subject-matter comprehension. An analysis by Jonathan Fife, director emeritus of the ERIC Clearinghouse on Higher Education, described inaccuracies when bell-curve analysis is used to judge students. He reviewed experimental data where teachers were told they were being assigned high-achieving students but actually were given random cross sections of students. The students in these classes scored highest in the grade level on the end-of-year standardized tests in Fife’s study.

He interpreted these and other results to support the theory that belief in students’ success can influence their learning. As such, learning-outcome differences can result from believing that all students have high potentials rather than expecting that only a few will be highly successful. The latter is the expectation dictated by the bell curve. Fife’s interpretation is that students can meet high expectations for performance when they have the opportunity to be exceptional and when effective educators provide the instruction.

When the goal is to discover what students have mastered in a course, the bell curve does not apply. Having a low end that is an equal match of the high end gives students the message that half of them will perform up to but not beyond a midpoint. Students respond to teacher expectations, so why restrict those expectations by imposing an artificial limit?

A Postscript
When my best efforts to explain the importance of positive, formative assessment — rather than the punitive feedback of bell-curve grading — failed to convince the administrator of the school where I had been teaching, I did not return to that school. When I interviewed for the teaching position I now enjoy at Santa Barbara Middle School my first question for the head of the school was this: “Do you require teachers to grade on a bell curve?”

Headmaster Steveo Lane responded: “Why would anyone still do THAT?”

Judy Willis is a math teacher at Santa Barbara Middle School in Santa Barbara, Calif. E-mail: A neurologist, she is the author of Research-Based Strategies to Ignite Student Learning, Insights From a Neurologist and Classroom Teacher.