Bloom’s Curve

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One of the most interesting contrasts in grading philosophy is the question of whether grades are meant to identify talent or to develop it.  

This is a simple, basic distinction that I have encountered over and over again in my research into the work of Thomas Guskey.  It is also a profound distinction that I believe all teachers are advised to consider.

A great example of this distinction is to be found in Guskey’s 2011 article, “Five Obstacles to Grading Reform.” I don’t like that title; there are so many negative associations I have developed in response to “reformers” of all stripes and agendas.  But that aside, it’s a great illustration of the simple distinction above: to identify or to develop?

In Guskey’s view, many Americans grew up in schools whose grades emphasized ranking.  A “C” meant you were doing average work compared to your classmates, while an “A” meant you were doing stellar work compared to classmates.  This is the concept of “grading on a curve.” Guskey believes that this is wrong for several reasons.  

Grading on a curve, which gained its historical traction long ago under the belief that humans’ IQ scores follow a similar bell-curve pattern and therefore academic achievement should presumably reflect that.  The problem is that this pattern should only remain true as long as no intervention steps were taken.  In other words, the goal of good teaching should be to change this pattern so that — in theory — all students should demonstrate the ability to score well on assessments.  The goal for educators should not be to select talent, but to develop it.  The idea is that — and here’s what’s fascinating — all students should be able to end up on the far end of the curve.  

If you have taught well, the bell curve of typical achievement should look very, very different.

Here, Guskey is going back to Benjamin Bloom’s theory of Mastery Learning.  Guskey by 2011 has been writing about this topic for many, many years, a sort of spokesman for the theory, continually putting it back at the forefront of educational research and theory.  Bloom’s goal was the very opposite of talent-selecting assessments such as the SAT: he wanted to reduce variation in student achievement.  He wanted the curve skewed to the high end by providing students with varied methods of instruction and varied amounts of time.  In short, he wanted learning to become the constant, time the variable.

In this 2007 article, Guskey did something that I always appreciate: he provided a historical context and a research-based approach for attacking a contemporary issue.  The contemporary issue was “achievement gaps” — the student variation in learning as particularly identified under NCLB.  The historical perspective he provided was to frame these achievement gaps as Benjamin Bloom’s variation in student learning, and to identify and hold up Bloom’s Mastery Learning as a promising approach.  

Bloom’s work noted that most teachers engaged in little differentiation of instruction.  As Guskey writes:

“Students for whom the instruction and time were inappropriate due to differences in their backgrounds or learning styles tended to learn very little. In other words, little variation in teaching resulted in great variation in student learning. Under these conditions, the pattern of student achievement was similar to the normal curve distribution shown in Figure 1.”

Figure 1, below, resembles a normal bell curve:

Bloom, inspired by earlier efforts to individualize instruction, sought ways to approximate the “ideal” learning environment: an individual tutor who tailors teaching directly to a student’s preparedness and interests.  Bloom designed a system of formative assessments, feedback, corrective activities, secondary formative assessments, and summative assessments — all with the goal of giving all students the time and teaching needed to learn well.  As a result of this practice, which Bloom called “Learning for Mastery” and then simply “Mastery Learning,” the curve itself would be changed to something like Figure 2, below:

Now, is this realistic?  That’s a whole different question — one that I’ve been writing about and thinking about and working through as an on-the-ground teacher under Proficiency-Based Learning for several years.  But practical concerns aside, those two graphics above illustrate something helpful to remember: here in Vermont, Proficiency Learning is all about reducing variation in student achievement.  That’s it.  That’s the goal.

The notion that follows from this is striking: If you are doing your job correctly, all students should be scoring highly and doing well.  That’s the goal in instruction, and that’s the goal in assessment.  Everyone should be doing well.

That does not mean, of course, lowering standards.  And it does not mean that this result is realistic.  And it brings up a whole host of questions about what should be valued in classrooms (for example, is it important to learn material more quickly?  Should that be reflected in grades?  What do more advanced students do while slower students keep learning the same material?).  

But no matter what, everyone on the right side of the curve is the goal, to me, that all teachers should keep in mind.  It’s incredibly simple, but also profound.


Yet here’s the problem with these academic approaches, like Guskey’s:

I think the public cares more about ranking than about knowing whether children learn.  

Guskey writes, “Grades based on students’ standing among classmates tell us nothing about how well students have learned. In such a system, all students might have performed miserably, but some simply performed less miserably than others.”

Fine.  But I actually think most parents don’t care that much about how well students learn about the Civil War, or photosynthesis, or the worldview of minor characters in obscure Russian novels.  To me, this is the mistake that we educators often make: We start to think that the mysteries of our narrow subject matter is the be-all and end-all of of existence.

I mean, if we’re being honest here, we’re not exactly really a culture that values learning for its own sake, right?

Even if you back away from traditional subject matter and have a class where students are being asked to learn “real-world” skills — say, culinary arts — I think most parents would prefer to hear that their child is doing better than his peers rather than that he’d developed “proficiency” in grilling a variety of meats. And would a parent really be too alarmed if a kid’s report card showed “needs Proficiency in the art of creating souffles.” Parents just want Johnny to be able to graduate and get a job at TGI McFunster’s.

It’s the same no matter what. Parents who value school usually want the reassurance that their kids are doing better than other kids.  It sounds horrible to say, but I think it’s true. Parents of children who struggle want to see that they’re going to do enough to “pass,” and the parents in the middle want a mix.

As long as it wasn’t stopping their child from graduating / getting into college / getting a scholarship, very few parents would really be crushed if their child wasn’t coming out of school with a good understanding of . . . well, fill in the blank. Pretty much anything. That’s just not the kind of society we are. Add in this very American notion of rewarding hard work and punishing laziness, and you’ve got even more demand for grades that rank.

Now, should it be an important goal of schools to downplay competition and ranking, and to keep the focus on each learner’s journey?  You could certainly make that case (and I have).

But that doesn’t change the fact that as a culture we value grades as normative ranking tools.  It’s deep in our DNA. And I don’t see that going away anytime soon.