Keeping it simple

Cognitive Load Theory (CLT) and effective teaching

Discovering CLT was a eureka moment for Steve Garnett – so important he felt compelled to write a new book for teachers. Here he shares 4 key ideas.

A big claim

Recent interest in cognitive load theory (CLT), has no doubt been stimulated by a tweet from Professor Dylan Wiliam in January 2017 – when he wrote, ‘I have come to the conclusion Sweller’s Cognitive Load Theory is the single most important thing for teachers to know.’

This is quite a claim. The tweet both intrigued me and worried me in equal measure. Firstly, I didn’t really know how this theory could impact on teaching and learning in real classrooms with real pupils; and secondly, I was concerned that I may have a significant gap in my knowledge around effective pedagogy.


What is CLT?

So, I set about trying to put this right and found out that it is important. Very important. What does ‘CLT’ propose? In brief, Cognitive Load Theory, developed by Professor John Sweller in the late 1980s, advises against overloading a learner’s working memory with excessive detail or complexity as he or she passes through each successive stage of a learning process. In my view, this is especially important when a learner is a novice, to whom a raft of new ideas, skills and concepts are just being introduced.

4 key ideas when using CLT

CLT has profoundly affected my approach to teaching and learning, and I believe it could really help others, as I have summarised in Cognitive Load Theory: A handbook for teachers

To get started with the idea, here is a checklist of some key takeaways that any teacher might benefit from in their day-to-day planning, by taking CLT into account:

1. CLT and the novice learner

When I see blogs or tweets related to CLT I don’t think quite enough emphasis is made about its relationship with the ‘novice’ learner. What I mean by this is that the storage capacity of working memory is especially limited and finite, and most keenly felt by the learner with limited or non-existent prior knowledge, i.e. the novice. However, if a learner already knows and understands a lot – that is, more ‘expert’ or ‘fluent’ – then their working memories can actually handle an enormous amount of ‘detail’ and there are no known limitations in terms of storage capacity.

2. CLT friendly approaches

When people suggest a particular ‘instructional approach’ that is CLT ‘friendly’, then this should be used in the classroom at the beginning of the learning journey – in other words, when their pupils are still at the novice stage and have not yet gained any mastery in the subject. As pupils gain expertise then other approaches to teaching and learning, such as discovery learning or problem solving, are more likely to be successful and can therefore be utilised.

3. Avoid working memory overload

Specific strategies a teacher can use in the classroom to avoid overloading working memory for the novice learner include:

  • Ensuring any labels on diagrams are written as close to the thing it is labelling as possible.
  • Having lots of key visuals ready to accompany a verbal exposition (but don’t make the verbal exposition too long!).
  • Not reading text out loud to pupils if they are also attempting to read it at the same time. If you have to, do it in very short bursts with regular recaps with the pupils. The ideal, however, is to ask the pupils to read it first or better still out loud. (Of course, this might make for a noisier classroom, but ironically a more productive one in terms of a stronger recall of what has been read.)
  • Using plenty of worked examples initially when pupils are first shown a particular skill or method, and then gradually change this to partially completed examples – asking the pupils to complete any missing elements.
  • Enjoying the ‘white space’ on handouts or worksheets. Resist the temptation to over-detail a resource. Better to have several pages of handouts each with plenty of white space on them rather than putting too much into one sheet.

4. Less is more

More broadly, think ‘less is more’ when teaching the novice learner. This way you are less likely to overload the limited capacity within working memory. For example, think about:

  • Limiting the amount of teacher talk to the absolute minimum.
  • Limiting the number of instructions pupils receive to a maximum of 3–5 and avoid speaking at length. Better to chunk things with mini-recaps.
  • Using visuals to convey key ideas and meanings. Ideally these should have minimal detail, so go for icons rather than detailed images.
  • Making sure any written words that pupils are exposed to concentrate on Tier 3 vocabulary mainly. These are those crucial domain-specific technical terms that are necessary to develop deep understanding (examples include ‘polygon’ in maths, ‘tectonic processes’ in geography or ‘monologue’ in drama).
The importance of CLT

This overview should certainly get you started with CLT. I believe my teaching would have improved immeasurably if I’d attended more effectively to the needs of my novice learners with some of the techniques described above – and, as a result, pupil outcomes would have been far better.


Steve Garnett is a trainer, teacher and educational thinker. He is author of The Subject Leader: an introduction to Leadership and Management, published by Crown House Publishing in 2012. . His new book, Cognitive Load Theory: A handbook for teachers (Crown House Publishing, 2020) is out now and is available with 30% off + free UK P&P using code NQT30 (offer expires 31st December 2020).

Steve delivers both online and face-to-face training globally on CLT and shares how to embed it into everyday teaching and learning.

He can be contacted at:


Feature Image: by Marco Antonio Reyes from Pixabay