The role of forgetting as we learn

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Date published 20 April 2018

The starting point for the design of a science of learning session at an Ambition Institute conference was my own experience and frustrations as a teacher.

I gained great satisfaction from pupils achieving ‘lightbulb’ moments in lessons where they appear to ‘get’ a new idea, but this was often countered by bitter disappointment when I came to assess learning at a later date and often discovered that such breakthroughs were ephemeral.

An uncomfortable truth is that, however ‘great’ our teaching of a lesson, our pupils will forget much (if not most) of the new learning.

However, the fact that we forget new information doesn’t mean that the learning was wasted. Back in the late 19th Century, Hermann Ebbinghaus noted that we relearn information much faster and retain it for longer when we return to it. This suggests that information isn’t truly lost when we forget it, but a trace remains which can be potentially strengthened and consolidated.

Ebbinghaus forgetting curve

Memory research for the classroom

Our capacity to store information in long-term memory appears limitless – psychologists genuinely don’t know the upper bounds of our ability to store experiences. However, psychologists Robert and Elizabeth Bjork suggest that such memories have a retrieval strength and a storage strength.

Retrieval strength determines how readily we are able to recall information. Storage strength determines the durability of the memory. When we have just taught some material, it is likely that it will have a high retrieval strength.

As teachers, we tend to provide lots of additional cues to help pupils recall information (giving hints or having wall displays with key information), or pupils may ‘outsource’ the memory to pen and paper. However, whilst these strategies probably help pupils immediately recall the new learning, it’s likely that the storage strength of the memory is still very low.

"Our capacity to store information in long-term memory appears limitless – psychologists genuinely don’t know the upper bounds of our ability to store experiences."

On the other hand, sometimes we have memories which are long stored but we struggle to bring them to mind when we need them. Sometimes we know that we know something, but we can’t quite remember – it’s on the tip of the tongue. Even if a memory has a high storage strength, it doesn’t mean we can easily access it. In these cases, it’s likely that the long period of time since we last had to recall the information means that the retrieval strength of the memory is very low.

Forgetting boosts learning

We’d like pupils to have both high storage and high retrieval strength for the facts, vocabulary, concepts and skills which they learn; but to achieve this, they will likely have to access the memory many times over a long period.

Perhaps the most surprising finding in this field of research is that forgetting is a vital part of learning. While the retrieval strength of a memory is strong (i.e. we can effortlessly bring it to mind) the gains to storage strength from practising recalling that information is very low. However, as the retrieval strength of a memory declines over time, there’s a bigger gain in storage strength when we try to retrieve it. As Robert Bjork puts it, “Forgetting, rather than undoing learning, creates the opportunity to reach additional levels of learning.”

Counter-intuitively, letting our pupils forget might be the best way to increase their learning.

I think this has a number of useful implications for teaching and for how we teach pupils to become more independent in their learning. Exploring these implications and asking critical questions about the evidence they are based on, is a useful starting point for teachers being able to put evidence to work in the classroom.

This article originally appeared on the website of the Institute for Teaching. In March 2019 the Institute for Teaching merged with Ambition School Leadership to form Ambition Institute.

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Nick Rose
Nick Rose
Fellow, Learning Design

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