Educators: Don’t Assume A Can Opener

by Guest Blogger
March 11th, 2014

By Paul Bruno

Paul Bruno is a middle school science teacher in California. This post originally appeared on his blog:

There is a famous joke about the way economists often undermine the usefulness of their conclusions by making too many simplifying assumptions. Here’s one of the older formulations:

There is a story that has been going around about a physicist, a chemist, and an economist who were stranded on a desert island with no implements and a can of food. The physicist and the chemist each devised an ingenious mechanism for getting the can open; the economist merely said, “Assume we have a can opener”!


(Imaginary can opener courtesy of Shutterstock.)

It’s probably not fair to pick on economists in this way when the abuse of simplifying assumptions is at least as widespread in education.

For instance, arguably the trendiest thing going in education today is ‘grit‘: “the tendency to sustain interest in and effort toward very long-term goals”.

We all agree, I suspect, that a tendency to persevere is desirable, and that we should prefer that students have more of that tendency than less of it. So it is perhaps not surprising that since the term was popularized by researcher Angela Duckworth many teachers and schools have begun reorganizing their work to better promote and instill ‘grit’ in their students.

And yet, here’s Duckworth being interviewed by Alexander Russo last month:

Can you talk about how to teach grit in the classroom?
AI don’t know that anybody’s totally figured out how to teach it: What do you do exactly, even when we do have insights from research? How do you get your teachers to speak in ways that support growth mind-set? That’s why, through a nonprofit I helped cofound called the Character Lab, we’re organizing some lectures for teachers about self-control, grit, and related topics. It’s not totally prescriptive, because the science is still developing.

Not to put too fine a point on it, the world’s leading expert on grit is saying that educators who are substantially altering their work to better teach grit are doing so without much in the way of scientific backing or guidance.

In other words, in their excitement over grit many teachers and school leaders have simply assumed – without justification – that it is a trait that can be taught and that they know how to teach it.

This is by no means a problem limited to grit. Before grit it was “21st century skills“, “social-emotional learning”, “critical thinking”, or “scientific thinking”. What unites these fads is that they all, to varying degrees, suffer from a lack of rigorous scientific evidence indicating that they can be taught at all, let alone that we have reliable ways of teaching them in schools. (“Fluid intelligence” may be next.)

Meanwhile, we have good evidence indicating that schools today are reasonably – if imperfectly – effective at teaching kids the less-glamorous knowledge and skills – e.g., in math, science, and history – that we associate with “traditional” education.

So while it’s a good idea for researchers and educators to experiment with methods for teaching other, “higher-order” or “non-cognitive” abilities, it’s also important to remember that it is probably premature to ask schools to move away from their core competencies if we can’t also give them a clear alternate path forward.



  1. Grit, persistence, cannot be taught, because it is a habit, and habits are acquired by doing. That is, one becomes persistent by continually being persistent, until it becomes automatic. This is true of most of the skills that I was expected to be teaching in the progressivist system I was in, for example (and there is a long list: thinking well, attention,…). I believe that school can contribute to children acquiring these habits by teaching those “less-glamorous knowledge… such as math, science, history… that we associate with “traditional” education.”

    It seems that we have been expecting children to learn the content subjects, whichever they choose to learn, on their own once we have properly taught them the “skills.” However, it is more correct to say that children will acquire those good habits when we teach them the content subjects–which I call knowledge about what the world is.

    Comment by Susan Toth — March 11, 2014 @ 11:18 am

  2. Mr. Paul Bruno’s comment could not be more appropriate today. Forty-six states have adopted the Common Core with no evaluations at all-no pilot projects, no demonstration projects, and most important of all no carefully controlled scientific experiments that were published in a peer reviewed journal. The educational community must reject ideas, proposals, author’s opinions and fads unless they have been subjected to careful scientific study. Mr. Bruno is also correct in saying that teachers should continue to teach all traditional subject areas in traditional ways unless there is proof other subjects and methods have been shown to be substantially better!

    Comment by David J. Krupp — March 11, 2014 @ 11:31 am

  3. Indeed one does not teach ‘grit’; you create opportunities in the classroom for students to be gritty, and either they will, won’t, then figure out how to be gritty or grittier.

    Comment by Peter Ford — March 15, 2014 @ 5:00 pm

  4. It’s interesting that you wrote: “In their excitement over grit many teachers and school leaders have simply assumed – without justification – that it is a trait that can be taught and that they know how to teach it.” If you replace “grit” with “common core,” it’s nearly the same sentence — except it’s test/policy makers instead of teachers and they assume all kids can pass it or that teachers have access to the resources and materials to test. Since the later is not true and social promotion kills the idea of students actually being “proficient,” would teachers aligning curriculum help with the grit you speak of?

    Comment by CollJohn — March 20, 2014 @ 12:36 am

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