The Forgetting Pit

What is learning and how does it happen? These are key questions for anyone involved in education.

In The Teaching Delusion, as many authors have before me, I discuss learning in terms of long-term memory. However, in this blog post I would like to consider learning in a related but different way. I would like to consider learning in terms of a Forgetting Pit

Paying attention and thinking

We learn by paying attention to information and thinking about it. 

When we pay attention to information, it enters our working memory:

Working memory is where thinking happens. 

However, working memory is limited in terms of how much information it can hold and how long it can hold it. Accordingly, information doesn’t stay in working memory for long. Instead, it quickly moves into the Forgetting Pit:

The Forgetting Pit

The Forgetting Pit is an alternative way to think about long-term memory. 

Everything we pay attention to falls into the Forgetting Pit. However, not everything that goes into this pit is forgotten. Most of what we pay attention to is forgotten, but not everything. 

In general, it is a good thing that we forget information. If we remembered everything that we paid attention to, we’d quickly go mad! The job of the Forgetting Pit is an important one.

However, in teaching, it’s also a frustrating one. There are particular things that we want our students to learn but the Forgetting Pit makes this tricky. Understanding how the Forgetting Pit works is essential if we are to understand the teaching and learning process.

The Point of No Return

Information can be said to be ‘forgotten’ if it can’t be brought back out of the Forgetting Pit into working memory, despite prompts and reminders. 

The reason it can’t be brought out is because it has fallen too far down the pit to be retrieved. It has gone past the Point of No Return:

Most of the information we pay attention to falls past this point. However, not all of it does.

Sticky information

Some of the information we pay attention to sticks to the walls of the Forgetting Pit. This is learning. The better stuck to the wall something is, the better it is learned. Information which has been learned (that is, stuck to the wall) can be retrieved:

How easily retrieved information is depends on how far down the pit it has gone. The further down the pit something is, the more difficult it is to retrieve:

The tendency to forget

One of the laws of learning is that we tend to forget. 

With few exceptions, everything we have learned is moving down the Forgetting Pit. Being stuck to the wall doesn’t stop information from sliding down. The rate at which it slides isn’t the same for everything, but most information is sliding down the pit.

What this means is that we can learn something well – it can stick tightly to the walls – but over time, because it is sliding down, it is less easy to retrieve than it was. 

Eventually, many things that we had learned well and could once easily retrieve, have moved past the Point of No Return and are forgotten.

The rate of forgetting

How fast things move down the Forgetting Pit depends on various factors, including how well information has stuck to the wall (how ‘sticky’ it is) and whether or not it has attached to other information (which will stop it moving as quickly). This latter idea is often referred to as schema:

One of the goals of teaching is to ensure that information sticks to the walls of the Forgetting Pit strongly enough that movement down this pit is as slow as possible.

If we are to be successful in achieving this, we need to understand why information sticks to walls.

Why does information stick to walls?

Information sticks to the walls of the Forgetting Pit because of the coating it is given in working memory.

Information in itself doesn’t have a coating. The coating is added when we think about information in working memory. If you don’t think about it, it doesn’t get a coating. Information which doesn’t have a coating can’t stick to the walls of the Forgetting Pit. Accordingly, it will be quickly forgotten, falling past the Point of No Return.

Revisiting and retrieval

Information which has a coating can stick to the walls of the Forgetting Pit and can be retrieved. When we retrieve it, we bring it back into our working memory.

Every time information is brought back into our working memory, the stickier the coating on it becomes. This means that the more we ask students to think about particular information, the more likely it will acquire the coating necessary to stick to the walls strongly. In other words, the better we will learn it.

Getting students to actively retrieve information (‘retrieval practice’, such as via closed-book quizzing in class or self-quizzing at home) results in a stickier coating than if students passively revisit information, for example, by re-reading it in a textbook or re-writing notes. When this retrieval is spaced out over periods of time, for example, using Daily, Weekly and Monthly Review, the coating gets stickier and stickier.

Similarly, if information we have stuck to the walls in the Forgetting Pit can be retrieved and linked to new information we encounter, for example, by creating a concept map, this new information is less likely to fall down the pit and be forgotten. It benefits from the stickiness of the information we already had.

The ‘Easily Retrieved Area’

As teachers, the area of the Forgetting Pit we want all learning to be in is the ‘Easily Retrieved Area’. This is the area from which students can retrieve things quickly, as and when they need to: 

Examples of things which most people have in the Easily Retrieved Area are:

  • Their name
  • The name of the Prime Minister
  • The answer to the sum: 2 x 10

However, normally, things don’t stick to the walls in this area the first time they are encountered. Some things do, but most things don’t. Instead, they tend to either stick to the walls further down the pit – meaning they can be retrieved, but not as easily – or don’t stick to the walls at all – meaning they are forgotten. 

A key question for all teachers to consider is: how do we get things to stick to the walls in the Easily Retrieved Area? 


Ultimately, learning is only worthwhile if we are able to use it. The catch-all term for this is ‘performance’. Performance is the application of learning. It is learning in action. 

Examples of performance include:

  • Naming the capital of Australia
  • Explaining the causes the Russian Revolution
  • Playing David Bowie’s Life on Mars? on the piano
  • Drawing a portrait
  • Solving an unseen mathematics problem
  • Making sense of what you are reading

In order to perform any task, we need to retrieve relevant information from the Forgetting Pit:

The more relevant information we have in the Easily Retrieved Area, the better our performance is likely to be. We have to work harder to retrieve information which is stuck to the walls further down the pit, which tends to negatively affect our performance. 

To perform as best we can, we need to be able to retrieve relevant information easily. As teachers, we don’t just want information to stick to the walls anywhere in the Forgetting Pit – our aim should be to get it to stick to the walls in the Easily Retrieved Area. 

Short-term vs long-term learning

Performance helps to make learning visible and provides evidence of what has been learned. However, as we know from our discussion of the Forgetting Pit, learning isn’t a fixed entity. Things we have learned – that is, things that have stuck to the walls of the Forgetting Pit before the Point of No Return – don’t stay learned. Movement down the pit is inevitable.

This means that while performance which draws on newly acquired learning can serve as evidence of short-term learning, it can’t be used as evidence of long-term learning. Things that were in the Easily Retrieved Area at the end of a lesson won’t necessarily be there when students arrive at the next lesson.

For example, imagine you are teaching students about ionic bonds. If, at the end of the lesson, students can correctly answer a series of questions assessing this knowledge, this would be an example of performance based on short-term learning. It is important to assess this, because it helps you to see whether or not the correct information has stuck to the walls of the Forgetting Pit.

However, being able to answer these correctly at this stage in the learning process only tells you about short-term term learning. If students can still do this a week later, this is performance based on longer-term learning. Being able to do this then would tell you that there hadn’t been much movement down the Forgetting Pit, which would be a good thing.

But will students still be able to correctly answer similar questions in six months’ time, in a year’s time or in six years’ time? The answer depends on how successful the Forgetting Pit has been at doing its job and how successful you and your students have been at stopping it from doing this.

Great teaching is all about trying to stop the Forgetting Pit from doing its job with the things that matter most.

The Forgetting Pit is discussed in The Teaching Delusion 3: Power Up Your Pedagogy by Bruce Robertson, published by John Catt Educational. Available at:

1 Comment

  1. Very interesting.
    When discussing study skills with students I also use the slippy wall and how we can make things stick.
    I think it takes more than good teaching, especially in the upper school. I think it takes “good learning” in the student’s own time. I have found that things stick much better when the student has created something: e.g. summaries of some kind: any kind which suits the student, to use the summary.
    I think your book covers these points in a similar way.
    All the best.
    Norman Roxburgh


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