The single most important thing for teachers to know… Version 2

WIliam CLT

Dear Reader,

Yesterday I published a post on Cognitive Load Theory (here) and how I use it in class. I was concerned that although I had been careful in my reading, I was sure to have “invented” modifications of my own (also known as “mistakes”). Sure enough, several readers kindly (and gently) pointed out where I had been creative/careless/wrong. My thanks especially to  ,  for his great essay here and @FurtherEdagogy.

This is version two of my post.

Please continue to comment – and never assume I am an expert.



Cognitive Load Theory, and How to Use It 2.0

Here is my explanation for how Cognitive Load Theory works and how to use it.

CLT schematic (3)
The elements of Cognitive Load Theory – long-term memory, working memory and external memory.

First comes the model of the mind.

In my simplified version of the model, there are three elements: working memory, long-term memory and external memory.

Long-Term Memory

Our long term memory stores knowledge and schemata – knowledge organised in useful ways. Schemata include:

  • social knowledge – people, interactions, relationships.
  • subject knowledge – e.g. knowledge about astronomy or the Tudors or rivers.
  • reading knowledge – how to decode, vocabulary, knowledge about layout, diagrams etc.

Our aim as teachers is to develop our students’ long-term memories. This what makes students more knowledgable, better problems solvers and more creative.

Working Memory

Working memory is where we store information which we need to use to complete a task, but which is not stored in our long-term memories. The information might include:

  • data to solve the task.
  • information about the task.
  • relevant processes.
  • novel social interactions/relationships.

The important thing for teachers to remember is that working memory is easily overloaded – three things to remember is usually too much. If you are asking students to carry out a novel task collaborating with new people using data they haven’t memorised, and hope that they will be able to reflect on their learning at the same time, you may be out of working memory, and out of luck.

Of particular importance to teachers is the evidence that solving a problem at full stretch does not allow students to reflect on the process – a vital part of learning. So, even if the learner gets the problem right, you may have wasted learning time. (Unless the problem was really important – like, say, a cure for cancer, or how to make the perfect cup of tea. Most class problems aren’t valuable in their own right).

External Memory

When the task gets tricky, working memory gets strained. That’s why we resort to counting on fingers, scribbling on the backs of envelopes, and working with someone else. Making use of external memory is a powerful strategy to relieve some of the pressure on working memory. Teachers should show students how to make use of it.

Using Cognitive Load Theory in Lessons

CLT schematic learning
Maximsing learning, by reducing the load on the working memory.

When our students learn, they are developing the schemata in their long-term memories. Our main job as teachers is to boost students’ schemata. This means thinking hard about what we want our students to be able to recal instantly and with little effort.

The key strategy suggested by CLT is reducing the amount of extraneous information held in working memory. The tasks you set should be challenging, but you overload working memory, the student will learn little.

I have written about several methods for improving learning using Cognitive Load Theory in previous blogs:

Using worked-examples and completion-problems to reduce cognitive load.

Reducing cognitive load by going goal-free and using cooperative learning.

Reducing the split-attention effect.

I think cooperative learning strategies are going to play an increasing role n the classroom as we develop our teaching in the light of CLT. I am currently working with Jakob Werdelin on develping cooperative reading strategies and will write more on this soon.



  1. A lovely post. Thanks for it!

    One thing that’s hard about CLT is that it’s hard to find teaching resources that really use the principles of the theory. One that I’ve found (and that I’ve found very useful in my teaching) is the Algebra By Example project:

    I can’t say enough nice things about their work and their development process (which was led by researchers invited by administrators to collaborate with teachers in the design of these materials). I think that it would be great if every subject and discipline had a large collection of worked-out examples for students to use in their learning.

    Looking forward to your next posts!


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