Cognitive load theory and how to make things stick!

"Why can't you remember how to write an essay? You wrote one last term!"

This is an all-too-common frustration voiced by teachers. From the teacher's perspective, it can seem as if students understand something in a lesson, only to forget it by the next. So, how can we ensure our students remember what we teach them? Cognitive load theory may hold the answers.

First devised by University of NSW Professor John Sweller and considered by famed British educationalist Professor Dylan Wiliam as the "single most important thing for teachers to know" [i], the theory is built on the assumption that working memory, while varied from person to person, is extremely limited. In fact, it is even more limited than we once thought (we can hold two to four pieces of information at one time as opposed to seven), and this fact has profound consequences for teaching and learning.

We can define learning as the "long term retention of knowledge" [ii]. In short, nothing is stored in long term memory; nothing is learnt. Cognitive load theory is concerned with how we can best increase long-term memory knowledge. To do this, the theory informs how we can most effectively design instructional techniques that ultimately reduce unnecessary working memory load [iii].

We can think of our working memory much like RAM (random access memory) in a computer. When a computer is fitted with lots of RAM, it can run multiple applications like Chrome, GarageBand and OneNote simultaneously without 'lagging', slowing down or producing the so-called 'spinning wheel of death'. The brain works in much the same way; only unlike a computer, there is a hard limit as to how much we can process in our working memory at any given time.

While we must impose a certain amount of necessary load or 'stress' on our working memory when learning any task of sufficient challenge, too often, this is accompanied by an 'extraneous load' that can often quickly overload working memory and dramatically inhibit learning. In an age in which students may be simultaneously trying to process a teacher's verbal instruction, an incoming email and phone 'pinging' in their pocket while navigating multiple digital platforms all in one lesson, cognitive 'overload' is all but guaranteed without careful consideration.

So, what are the effects of cognitive overload, and how do we mitigate against them to 'make $hit stick'?

Well, there are two particularly harmful effects researchers have found in our increasingly technologised teaching environment, namely the 'redundancy effect' and 'split attention'.

Let's start with the redundancy effect.

As Sweller notes, "most people assume that providing learners with additional information is at worst harmless and might be beneficial" [iv]. However, the redundancy effect shows us that it can, in fact, be detrimental to student learning as it essentially 'chews up' working memory space by attempting to take in too much irrelevant information. According to Mayer and Moreno, teachers need to get into the habit of removing redundant information in their lesson design that may detract from the desired learning outcomes [v]. Streamlining digital instructional resources through various processes, including "weeding", "aligning words and images more effectively" and the counterintuitive act of "replacing the combination of narration and onscreen text" with "narration and visual imagery" are just a few of the design changes that increase long term memory retention. [vi]

Split attention occurs when a student is asked to process two or more sources simultaneously. This may be across two digital learning platforms, such as OneNote and Seqta or within one medium, such as a PowerPoint slide. In these situations, the learner's working memory is placed under an unnecessary load as they must attempt to integrate information. Where possible, information must be physically integrated to reduce splitting the learner's attention.

In this age of information overload, cognitive load theory shows that it is increasingly imperative we do the careful work of curating our teaching resources and the learning environment in line with what the research tells us about memory and learning. The result is better learning outcomes, not to mention happier teachers.

Mr Sam Sterrett
Head of Enrichment

[i]Cognitive load theory: Research that teachers really need to understand, Centre for Education Statistics and Evaluation, September 2017
[ii]Webinar 003 | What Teachers Actually Need to Know about Cognitive Load Theory (with David Didau), Ed Tech, YouTube, 16 October 2020,
[iii] Veronikas, S. M., Shaughnessy, M. F., Le Doux, T. & Sweller, J., 'Interview with John Sweller', Educational Technology, vol. 46, no. 3, 2006, pp. 69–72,
[iv] Sweller, J., 'Story of a Research Program' in S. Tobias, J. D. Fletcher, & D. C. Berliner (series eds.), 'Acquired Wisdom Series', Education Review, vol. 23, 10 February 2016
[v] Mayer, R. E., & Moreno, R., 'Nine ways to reduce cognitive load in multimedia learning', Educational Psychologist, vol. 38, no. 1, 2003, pp. 43–52,
[vi] Mayer, R., Bove, W., Bryman, A., Mars, R. & Tapangco, L., 'When less is more: Meaningful learning from visual and verbal summaries of science textbook lessons', Journal of Educational Psychology, vol. 88, no. 1, 1996, pp. 64–73