What is Cognitive Load?

As teachers, we’ve all experienced that moment when a lesson seems to be going well—clear explanations, lively pace, lots of content—only to realise some pupils look overwhelmed, distracted or are simply not learning what your short-term lesson plan dictates they must know by the end of the lesson. It’s not always a question of effort or attention; sometimes, it’s just too much information at once. That’s where cognitive load theory comes in.

Rooted in research on how our brains process and store information, cognitive load theory offers powerful insights into why students struggle when lessons are overloaded—and how we can design learning experiences that actually stick. In this blog, we’ll explore what cognitive load is, why it matters in the classroom and, most importantly, how you can use it to make your teaching more effective, focused and manageable for your pupils.

The first word, cognitive, has the Latin root word ‘cognoscere’ which means ‘get to know’. Words using this root link to knowing something, such as ‘incognito’ (not knowing someone’s identity), ‘cognisant’ (knowing a particular fact) and ‘recognise’ (knowing someone from having encountered them before). Another hot topic within the classroom using this root word is ‘metacognition’, which is the ability to be aware of, reflect on and direct your own thinking.

Cognitive load theory was first developed in the late 1980s by psychologist John Sweller and suggests that a human’s working memory is only able to hold a small amount of information at any one time. You may have read one of our recent blogs about retrieval practice, which is a strategy where information is actively recalled from memory. Cognitive load is the amount of information that can be held in short-term memory to be built upon for a concept to transfer to long-term memory, and breaching the cognitive load that someone has is referred to as ‘cognitive overload’, meaning that some of the information that they were required to remember will have dropped out of their memory.

Psychologist George Miller’s ‘Magic Number’ theory from 1956 suggests that between five and nine items can be stored in short-term memory at any one time, and going above this results in some of the information being lost from short-term memory. Think about the last time you popped to the corner shop for a few bits; you might be lucky enough to be able to remember that you need a 4-pinter of semi-skimmed, toothpaste, the telly guide, a meal deal, some apples… oh, and maybe some washing up liquid too as you’re nearly out. On the way there, you bump into a friend and have a quick catch-up before continuing your journey. When you get to the shop, you can remember those important bits that you definitely need but the extra thing that you just thought of on the way out was just too much for your cognitive load (especially after gossiping with your friend about a mutual acquaintance’s new job) and the washing up liquid was a victim of cognitive overload. Situations like this are clearly why shopping lists were invented; avoiding cognitive overload can also translate to the classroom too, as outlined within this blog by the Chartered College of Teaching.

One of the worst perpetrators for cognitive overload in the classroom is a lesson presentation. In my first year of teaching, I spent far longer than was healthy (or, indeed, necessary) creating presentations where text zoomed in from the side then spun around, information was presented inside photo frames and images were as jazzy as possible. In my bid to make lessons visually engaging, I hadn’t considered how much pupils were being overloaded at a cost to their actual learning.

What is actually being covered in this slide? It’s a mystery. The heart is also an animated GIF that constantly pumps, just in case I actually had any pupils listening to me at this point in the lesson.

Following cognitive load theory, let’s strip this right back to the essentials of what pupils need to learn. Here are two examples of how this information could be presented more effectively and ensure that pupil attention is laser-focused on learning this new vocabulary, which I think was what I was reaching for in the monstrosity above.

Which do you prefer? Option A has the vocabulary presented within the diagram which does make it look a bit cluttered; option B uses letters and a key to keep the vocabulary separate to the diagram, using a technique called split-attention (where information must be processed from two or more areas).

Cognitive load theory suggests that option A is the far better example. In option B, there will be some children for whom looking at ‘vena cava’ in the key, reading that it’s represented by letter A, finding letter A in the diagram and then trying to recall that new term from the key is just too much (especially with having to repeat that process multiple times… by the time they’ve decoded which label represents the left ventricle, the chance of remembering where the vena cava is would be slim at best). Far better to have it all in one place, where working memory is not overloaded, learning is concise and the key information is clear – and not an emoji in sight.

It is also worth considering the cognitive load of verbal presentation too. Although we have established option A as the better option, if it is accompanied by a long-winded and overly complicated explanation with anecdotal stories then cognitive overload could be once again unfortunately achieved for some pupils.

Now that you understand cognitive load, a short-term task from this could be for you to reconsider one of the lessons you have coming up. Is there too much extra information? Is it presented appropriately? Can you explain it so that all learners understand within two minutes? Will pupil attention be solely on the teaching, or will other things distract them while teaching happens? Is the font used clear and not distracting? The EEF has published this fascinating blog which considers step-by-step the concessions needed to make a new concept as clear as possible for a secondary school pupil, which can easily be applied to primary learning (and it’s also reassuring to see retrieval practice as a cornerstone of this!).

In the meantime, reducing cognitive load has been a consideration for many of Classroom Secrets’s resources, so you can download presentations, worksheets and activities safe in the knowledge that they are designed to help learners focus on the key learning by removing redundant information, using a consistent style and supporting gradual learning over a resource, thereby reducing cognitive load and helping to alleviate any associated anxiety or worry. These will make a big difference to how well pupils absorb and retain what you are teaching them, ensuring a greater chance of success and retention of learning in long-term memory.

Images: Stock images