Why do our pupils forget what we teach them?

As Willingham (2009) points out, the human memory system is still mysterious even to the scientists who study it. We notice this strange reality everyday. Sometimes we forget why we walked into a room even though we waltzed through the door with purpose. In the middle of a conversation, we begin speaking and then forget what we were going to say. We put our keys down moments before and then forgot where we put them – later finding them in our pocket.

Despite this rapid forgetting, at other times we are able to recall stories from our childhood as if they happened yesterday. We can still remember the smells of the best (and worst) of our Mum’s cooking. Sometimes we are in situations and memories we thought we’d lost come back, searing into our consciousness, reminding us of something that makes the present situation more familiar than we first thought (often referred to as de ja vu). All of these events make our memory feel illogical, messy and difficult to understand.

In the classroom, as a teacher, forgetting can be particularly confusing. It’s a conundrum when pupils can vividly remember the visitor who came in Year 3 with weird Viking swords, yet three years on, they can’t remember the answer to 7 x 8 to complete a column multiplication calculation.

I am certainly not the first person to blog about this. Joe Kirby and Kris Boulton write eloquently about the issue (found here and here). However, in this post, I want to put down three simple reasons why forgetting might occur. But before this, we must understand why we remember.

Willingham (2009; 2017) once again in his work points us to a principle that lingers throughout the cognitive science research (Schacter, 2002) that helps explain some of what we know about the way that our memory works:

‘Our Memory is the residue of thought.’ – Willingham (2009, p.61)

In general, pupils remember the things they think about most (Schacter, 2002). I can remember a maths lesson I taught last year on counting using number lines that illustrates this. I used an example from my time as a competitive swimmer. I told a few stories about training drills that involved swimming certain distances of the fifty-meter pool. We swam a quarter of the pool, then stopped and treaded water. Then, we would swim to half way, then stop and tread water. Then to three quarters, then stop and so on. I created a white board slide with a little swimmer in a fifty meter pool and dragged him certain distances to illustrate how we could talk in maths about travelling ‘half’ of a distance, ‘a quarter’ of distance, three quarters of a distance and so on. I then discussed how they could work out what these measurements were in relation to fifty meters and other measurements.

The lesson turned into fanatical questioning about me being a swimmer, my life as a teenager, where I lived, how I learnt to swim and so on. It’s safe to say, they didn’t learn much maths in that lesson. They did learn a lot about me though.

What does this story articulate about memory? Well, for me, it shows that the ‘hooks’ and ‘contexts’ we might frame our lessons within can sometimes backfire because of the cognitive principle Willingham (2009) highlights above: our pupils remember what they think about. In the case of the lesson, they became obsessed for thirty to forty minutes with my life before being a teacher. This meant they thought about me a lot, which meant they didn’t think about measurements on a number line. My pupils focussed on the hook I wanted to provide, rather than the learning itself! As I said above: memory is the residue of thought.

The nature of forgetting: three possibilities[i]

So we’ve established why pupils might remember (because it’s what they think about most) but why do they forget what we’ve taught them? To understand this, we must consider a simple model of the mind and what might be going on in the grey matter between our ears. (You can follow my thinking using the diagram below for reference.)

Screen Shot 2018-10-05 at 17.31.57

This model is taken from Willingham (2009; 2017).

The working memory is where we keep things ‘in mind’ and it is probably where our ‘consciousness’ exists (Baddeley, 2007). This part of our mind is finite and can only keep a certain amount of information from the environment in it at any one time. This is unlike the the long-term memory, where apparently endless amounts of information can be stored. Cognitive scientists are yet to find the limit of our long-term memory storage potential (Pinker, 1997; Baddeley, 2007).

Information enters our working memory from either the environment or our long-term memory. The environment is full of information that we could take in at any one time. For example, you’re reading this blog post right now but outside there are cars going past on the road; there are birds in the tree in your back garden and there is toast in the toaster (don’t let it burn, please). You won’t notice the toast, or any of the other things, until you’re paying attention to them. As you’ll see in the diagram, information doesn’t end up in your long-term memory until it has first passed through the working memory.

When pupils ‘remember’ the learning we’ve taught them, they are retrievingit from their long-term memory store. Throughout this process, their minds are constantly pushing the remembered knowledge back and forth between the working and long-term memory (Roediger et al. 2011). In the process, they are forming stronger representations of that knowledge to be recalled at another time.

3 reasons for forgetting

So, with this mental model in mind, what’s going on when pupils forget what we teach them? Although there are others, here are three key reasons why.

  1. They weren’t paying attention (at least not to the right things)

What we’ve established so far is that we remember what we pay attention to. As teachers, we are often well trained in knowing whether a pupil is ‘engaged’ in a lesson. However, it is important that our lessons are well designed so that pupils pay attention to the right things. If a pupil has the opportunity to pay attention to the wrong things in a lesson, it will mean that it is unlikely that they will be able to transfer new learning from the environment to their long term memories.

Sweller’s (1998;1999) Cognitive Load Theory (CLT) can help to explain this a bit further. CLT, in brief claims that if there is too much to think about in a lesson, the working memory will be overloaded with information. Because of this, pupils will struggle to focus on the task and also not retain new learning. Therefore, CLT argues lessons to be designed so that pupils’ working memories can focus on the key learning for the lesson. By doing this, there is a stronger chance of that learning being transferred to the long-term memory.

  1. What they learnt in the lesson was never transferred to their long-term memory

What was in their working memory, where only a small bit of information can be stored, never successfully transferred to their long-term memory. Therefore, it could well have been that they performedwell in the lesson but they didn’t actuallylearnanything since it was never transferred to a long-term storage. In other words, whatever was there for that moment in the lesson, left their heads as they left your room for break.

  1. They genuinely forgot (or they couldn’t remember it)

The third and final option is that the knowledge they had once learned no longer resides in their long-term memory. It has actually been forgotten. Without going into too much detail, recent research suggests that it is a myth to assume that our long-term memory store everything picture perfectly (Willingham, 2009). Just because we can recover a few long lost memories through nostalgic episodes, it doesn’t mean that all memories can be recalled.

This final option is quite troubling for us as teachers (or at least for me). Why, if our pupils are paying attention to what we’ve taught them and we’ve made sure we go over it time and time and time again, do they still forget?

A short but reasonable explanation for this is that when we teach, we ought to get our pupils to think about the meaningof the knowledge or skills we are teaching them (this post discusses this in more detail (tag Kris Boulton here). Attaching what we teach to why it is being taught, what significance it has within the topic or unit, how it might be applied to other contexts are all really good things (Joe Kirby is very helpful here in this post).

Yet all is not lost…

In the later 1800s, Ebbinghaus (1885/1964) study of the human memory and his now infamous ‘forgetting curve’ first showed the way in which our minds will gradually forget over time. This hypotheses still stands as a viable explanation for what happens within our mysterious memories. However, Ebbinghaus (1885/1964) did claim that we can ‘interrupt’ forgetting by recalling information over time, spacing our retrieval out at regular intervals. In more recent years, Bjork’s research has shown that forgetting and then retrieving information can aid our memory:

“Forgetting, rather than undoing learning, creates the opportunity to reach additional levels of learning.”[ii]

Forgetting might actually might be a good thing…if we put it to good use.

So, how then should we teach related to this? I’ll try and answer that in my next post.


Baddeley, A. D., & Logie, R. H. (1999). Working memory: The multiple-component model. In A.Miyake & P. Shah (Eds.),Models of working memory (pp. 28±61). Cambridge, UK: Cambridge University Press.

Ebbinghaus, H. (1885). U¨ ber das Ged€achtnis. Leipzig: Duncker & Humblot.

Pinker, S. (1997). How the mind works. New York: Basic Books.

Roediger, H. L., Putnam, A. L., & Smith, M. A. (2011). Ten benefits of testing and their applications to educational practice. In J. Mestre & B. Ross (Eds.), Psychology of learning and motivation: Cognition in education, (pp. 1-36). Oxford: Elsevier

Schacter, D.L. (2002). The seven sins of memory: How the mind forgets and remembers. Boston: Houghton Mifflin

Sweller, J., (1998) Cognitive load during problem solving: Effects on learning, Cognitive Science, 12, 257-285

Sweller, J., (1999) Instructional Design in Technical Areas, Camberwell, Victoria, Australia: Australian Council for Educational Research

Willingham, D. T. (2003). How We Learn: Ask the Cognitive Scientist. Pupils Remember… What They Think About. American Educator, 27(2), 37-41. http://www.aft.org/periodical/american-educator/summer-2003/ask-cognitive-scientist

Willingham, D. T. (2004). Why Pupils Think They Understand-When They Don’t. American Educator, 27(4), 38-41. http://www.aft.org/periodical/american-educator/winter-2003-2004/ask-cognitive-scientist

Willingham, D. T. (2009) Why don’t students like school? San Francisco, CA: Jossey-Bass.


[i]There are other possible explanations for forgetting. This website goes into more depth (and is a bit more technical) than the post I’ve written here. http://thepeakperformancecenter.com/educational-learning/learning/memory/forgetting/

[ii]I got this quote from this post from the Institute of Teaching website. https://ift.education/why-forget/

4 thoughts on “Why do our pupils forget what we teach them?”

  1. You’re definitely on the right track with this; I’ve been reading “How I wish I taught Maths” by Craig Barton and he has two nearly identical chapters to this blog with the same references. Great minds think alike! Keep it up Robbie.

    Liked by 1 person

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s