Below are some of the key points from articles listed on the “Cognitive Load Theory links” page. As with the “Memory and Retrieval” summary and the “Mastery” summary, this is not intended to be a comprehensive review but rather a starting point for discussion and further work.

In January this year, Dylan William tweeted “I have come to the conclusion that Sweller’s Cognitive Load Theory [CLT] is the single most important thing for teachers to know.”

CLT- The “single most important thing for teachers to know”?

So what is this important thing? Dan Williams (1) tells us “Cognitive Load Theory (CLT)… posits that our working memory is only able to hold a small amount of information at any one time and that instructional methods should avoid overloading it in order to maximise learning (Sweller, 1988).”

The linked article (2) in Dylan William’s tweet outlines how CLT was developed by Sweller, and describes how his ideas were met with some hostility at first: “It was the worst possible time to be publishing papers calling into question the efficacy of using problem solving as a learning device… The research on worked examples was treated either with hostility or more commonly, ignored.”

Sweller describes how his rather formidable partnership with Kirschner and Clark was formed, and relates how their paper (3) from 2006 had an immediate (if rather polarising) impact, with its (perhaps rather provocative) title: Why Minimal Guidance During Instruction Does Not Work: An Analysis of the Failure of Constructivist, Discovery, Problem-Based, Experiential, and Inquiry-Based Teaching.

Whatever your opinion on Sweller and CLT, this is a fascinating read, both in terms of the research itself, and the struggle to be heard in an unreceptive environment. Now “technically” retired, Sweller doesn’t pull any punches, concluding: “I have at times, advanced suggestions that many felt were outrageous. Some of those suggestions now seem to be considered self-evident by many in the field. How did I change people’s views? I do not think I did. Rather, people retired or died to be replaced by younger people who did not have to carry the burden of their own long history.”

Working Memory

CLT centres around the impact that teaching strategies have on Working Memory (WM), summarised in the Scientific American (4): “Many suggest that working memory can store a limited number of “items” or “chunks” of information… Research has shown that the number of bits that can be held in memory can depend on the type of item—flavors of ice cream on offer versus digits of pi… An alternative theory suggests working memory acts as a continuous resource that’s shared across all remembered information. Depending on your goals, different parts of the remembered information can receive different amounts of resource… A different theoretical approach instead argues that the capacity limit arises because different items will interfere with each other in memory… And of course memories decay over time, though rehearsing the information that’s in working memory seems to mitigate that process.”

Willingham (5) talks about flexible and inflexible knowledge and argues that often when we think students are simply learning things “by rote” it is deeper than that “I would argue that most of the time when we are concerned that our students have acquired rote knowledge, they have not. They have actually acquired inflexible knowledge… Flexible knowledge is of course a desirable goal, but it is not an easily achieved one. When encountering new material, the human mind appears to be biased towards learning the surface features of problems, not toward grasping the deep structure that is necessary to achieve flexible knowledge.”

Sweller’s book (6) from 2011 gives a detailed and thorough account of CLT, and it has been beautifully summarised by Oliver Cavaglioni (7) to give a useful overview of the theory within it including:

  • The distinction between primary and secondary knowledge
  • Experts and memory- the role of memory, rather than game strategy, in becoming a Chess master, and the implications for novices, who need to use thinking skills, in contrast to experts, who can rely on knowledge.
  • Acquiring information, and how much of the secondary knowledge we store in long term memory is “borrowed”. This process is favourable when it links to knowledge that is already there.
  • Working memory has limited capacity and duration, and novices will need to use WM to process new information. We need to help them to access necessary knowledge from long term memory, and give them the cues that can help this process.
  • Intrinsic and extraneous cognitive load – the idea that we can only use WM to process ideas at first, but if we can link them to other elements and form schema, it imposes less load on WM.
  • It also summarises further theories and effects that link into the practical strategies below.

Examples of strategies

Direct Instruction

Clark et al. (8) argue that “while experts often thrive without much guidance, nearly everyone else thrives when provided with full, explicit instructional guidance (and should not be asked to discover any essential content or skills).” 

Rosenshine cautions (9) that we must be sure what we mean when we talk about direct, or explicit, instruction, and gives a number of meanings and approaches to help students learn effectively.

Dual Coding

This is not about drawing! The Effortful Educator is very keen to point this out because “I am the antithesis of creative… Today, after living 33 years on this planet, I still am unable to write on my board in a manner allowing all students comprehension. My 5 year old son, Eli, has mastered the art of drawing people, rockets, and dinosaurs; I’d settle for being able to draw a really cool stick person.” (10)

Pritesh Raichura (11) gives examples of how he has used Dual Coding in Science, and offers these guiding principles:

  1. Keep the diagram very simple, focussing only the elements important to the explanation. This avoids distractions that result in cognitive overload.
  2. Avoid sacrificing accuracy for clarity where relevant.
  3. Text/verbal information must complement the image.
  4. Ask yourself if an image is necessary.
  5. Ask questions throughout to check for understanding.

Worked Examples

Dan Williams (1) explains why worked examples should be used: “There are a wealth of studies that have shown the positive impact of using worked examples to enhance learning (Chandler and Sweller, 1991). According to Clark, Nguyen and Sweller (2006, p.190), ‘a worked example is a step-by-step demonstration of how to perform a task or how to solve a problem’. These steps provide learners with direction and support to create mental models of how to tackle a problem/task, or what ‘good’ looks like. Discovery or problem-based learning on the other hand can be burdensome to working memory due to learners having insufficient prior knowledge to draw upon to support their learning.”

Ben Rogers writes about how he uses worked examples in Physics (12) and you can build on this idea by using strategies such as “fading” (6).

Cognitive Load and Practical Science

There has been some discussion recently about practical science, and how this can most effectively support learning. A series of blog posts by Dodiscimus (13) looked at the value of practical work in Science, and in the final post, he concludes “As science teachers, we need to be careful not to think that children see practical work the way we do, but if we ever lose the joy then it’s time to do something else.”

People have also examined how we can help students to learn from practicals in Science by reducing “the dangers of overloading practical lessons with too much for learners to take on”. David Paterson (14) gives an example of how learning can be broken down to better support understanding from practical work.

Questions to consider:

  • Which activities in Science place the greatest load on Working Memory? How can we reduce this?
  • Which of the strategies listed above would be worth considering? How and where might you use them?
  • How does practical work fit into all this?