Confirmation bias is the habit we all have of looking for evidence that confirms what we already believe to be true. It is pernicious. You do not need swagger and you don’t need hubris to fall foul of it. Confirmation bias is everywhere.

I have built many systems to attempt to improve my own teaching and, later, the work of my department. I could describe them in intricate detail, but that is not for this post. Instead, I will offer one factor that the more successful systems have in common – they seek disconfirming evidence.

In other words, these systems bake-in a confrontation with evidence that a teacher may not otherwise seek and probably does not want to know about.

Of course, that makes life tough at times. None of us want to learn that we haven’t taught a concept particularly well or worse, we haven’t taught it as well as our colleagues or worse, we haven’t taught it as well as the twenty-two-year-old who is six months into their career. It feels safer, easier and more comfortable to inhabit the abstract, invoking the myriad factors that affect learning as an excuse to ignore the one factor we can potentially control.

And it is understanding this need for disconfirmation that enables us to improvise and innovate around an established approach without reducing its effectiveness.

For instance, it is now clear to me that disconfirmation is critical for the effective use of formative assessment. We think we have taught something. Have they learnt it? Apparently not. Oh well, let’s try again.

And yet when formative assessment went large in the noughties in England, it turned into the opposite of an exercise in disconfirmation. Under Assessing Pupil Progress (APP), intricate rubrics were created for teachers to tick-off every time a student demonstrated, to an undefined degree of competence, a particular level of achievement. And then we all moved on. This was an exercise in confirmation bias.

In my latest podcast with David Didau, we briefly discuss David’s experience in England of poor implementations of a ‘knowledge-rich’ curriculum, a curriculum approach I would advocate. The key to whether knowledge-rich curriculums or explicit teaching are implemented effectively will be the role of disconfirmation. You cannot replicate the form of these approaches and still obtain the benefits you are expecting if you leave out mechanisms by which the truth about failure will hit you in the face. Without such mechanisms, these initiatives will be tried, will not deliver and will then be discarded in favour of next year’s initiative.

It may be worth thinking about.


One thought on “Disconfirmation

  1. Chester Draws says:

    The ultimate in lack of disconfirmation is surely schools who refuse to give end of year exams.

    In reality we know that students most of what they partly learn — and tend to remember only that which is securely locked in. If you don’t check at the end of the year, how can you know what was never properly learnt in the first place?

    It is a painful experience looking at your end of year results as student after student fails to apply skills that you spent weeks trying to get in. My current Year 9s all passed the Trigonometry end of topic test with ease earlier in the year, but half couldn’t do the simplest questions this week. If I didn’t have that end of year exam, then I would have been blissfully unaware how little that they had properly embedded.

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