Cognitive Load Theory: Why Less Can Help Children Learn More

Cognitive load theory has become one of the most quoted ideas in English schools over the past decade, from teacher training to staffroom conversations. The core of it is simple, and it has practical consequences for lessons and for homework at the kitchen table.

Where it comes from

The theory was developed by John Sweller, an Australian educational psychologist, from the 1980s onwards. In a 1988 paper in Cognitive Science, he looked at how people solve problems such as algebra or geometry tasks. A common method is means-ends analysis: you keep comparing where you are with where you want to be and search for moves that close the gap. Sweller argued that this kind of searching uses up so much mental capacity that little is left for noticing the underlying pattern of the problem. Learners can solve the problem and still learn very little from it.

The theory rests on a picture of human memory that Sweller, Jeroen van Merriënboer and Fred Paas set out in a 1998 review:

• Working memory, where we consciously handle new information, can hold and process only a few new items at once, and only for a short time. Nelson Cowan (2001) reviewed the evidence and suggested a typical limit of around four chunks for adults.
• Long-term memory is vast. It stores knowledge as organised structures, often called schemas.
• Once a schema is well learned, it can be pulled into working memory as a single unit. An expert reader sees a word, not a string of letters.

The practical upshot: novices have few schemas, so new material eats up their working memory quickly. Experts can handle much more because their knowledge does part of the work.

Types of load

Sweller and colleagues distinguish between kinds of demand on working memory.

Intrinsic load

This comes from the material itself, and in particular from how many elements must be held in mind at once. Learning the names of the planets has low intrinsic load because each fact can be learned separately. Solving a simultaneous equation has high intrinsic load because several relationships interact. Intrinsic load also depends on the learner: what is complex for a Year 7 pupil may be simple for a Year 11 pupil who already has the schemas.

Extraneous load

This comes from how the material is presented, and it does not help learning. Examples include a diagram on one page with its labels on another, so the learner has to hold one in mind while searching for the other (the “split-attention” effect described by Paul Chandler and Sweller in 1991), slides crammed with text the teacher is also reading aloud, or instructions that are vague, so effort goes on working out what to do.

Earlier versions of the theory added a third type, germane load, for effort that contributes to building schemas. In later writing Sweller treats germane load less as a separate source and more as the share of working memory a learner is able to give to the intrinsic load, once extraneous load is out of the way. You will see both versions in textbooks.

Worked examples

The best-known finding from cognitive load theory is the worked example effect. Sweller and Graham Cooper (1985) compared students learning algebra who studied worked examples with students who solved the same problems themselves. Those who studied the examples did better when later tested on similar problems.

A worked example shows every step of a solution. The novice does not have to search; they can spend their limited capacity on understanding why each step follows from the last.

The expertise reversal effect

The benefit does not last for ever. Slava Kalyuga, Paul Ayres, Paul Chandler and John Sweller (2003) reviewed studies showing that techniques that help novices can stop helping, or even get in the way, as learners gain expertise. A pupil who already knows the method has to process the worked example as redundant information. For them, solving problems independently becomes the better practice.

This is why teachers often move from a full worked example, to a partly completed one where the pupil fills in later steps, to independent problems.

What the theory does not tell us

Cognitive load theory is well supported in laboratory studies, but it has thoughtful critics. Ton de Jong (2010), in Instructional Science, raised several concerns:

• Most studies rely on a single self-rating of mental effort, which cannot show when a learner is actually overloaded and is hard to compare across studies.
• It is hard to separate intrinsic, extraneous and germane load in real studies, which makes it possible to explain almost any result after the event.
• Many experiments use short sessions with students new to the topic, under time pressure. Classrooms involve longer learning, prior knowledge and motivation, so findings do not always transfer neatly.

None of this means the theory is wrong. It means “reduce cognitive load” is a guide for design, not a precise measurement, and it does not tell us that challenge is bad. Hard thinking about the right thing is the point of learning.

In the classroom

• Teach new material in small steps, and check understanding before adding the next one.
• Use worked examples for new methods. Talk through why each step happens, then gradually remove steps for pupils to complete.
• Put labels on diagrams, not in a separate key, when the two must be read together.
• Strip out decoration. A slide with a busy background, animations and several fonts asks pupils to process things that have nothing to do with the lesson.
• Do not read out text that is already on the screen word for word. Either speak, or let pupils read.
• Watch for the reversal. When pupils are confident, extended guidance can become a drag. Offer the challenge task to those who are ready.
• For pupils with SEND, especially those with working memory difficulties, reducing extraneous load is often the single most useful adjustment: one instruction at a time, a visual checklist, and key vocabulary on the desk.

At home and with homework

• Before your child starts, check they know what the task is asking. Confusion about instructions is pure extraneous load.
• Clear the space. A quiet table with only what is needed lets more attention go on the work.
• If your child is stuck on a new type of maths problem, work through one example together, explaining each step aloud, then let them try the next one alone.
• Avoid teaching a different method from the one used in class unless the teacher suggests it. Two competing methods add load.
• If homework regularly ends in tears, tell the teacher. It may be pitched beyond what your child can manage alone, which the teacher needs to know.

Further reading

• Chandler, P. and Sweller, J. (1991). Cognitive load theory and the format of instruction. Cognition and Instruction, 8(4), 293-332.
• Cowan, N. (2001). The magical number 4 in short-term memory: a reconsideration of mental storage capacity. Behavioral and Brain Sciences, 24(1), 87-114.
• De Jong, T. (2010). Cognitive load theory, educational research, and instructional design: some food for thought. Instructional Science, 38(2), 105-134.
• Kalyuga, S., Ayres, P., Chandler, P. and Sweller, J. (2003). The expertise reversal effect. Educational Psychologist, 38(1), 23-31.
• Sweller, J. (1988). Cognitive load during problem solving: effects on learning. Cognitive Science, 12(2), 257-285.
• Sweller, J. and Cooper, G. A. (1985). The use of worked examples as a substitute for problem solving in learning algebra. Cognition and Instruction, 2(1), 59-89.
• Sweller, J., van Merriënboer, J. J. G. and Paas, F. G. W. C. (1998). Cognitive architecture and instructional design. Educational Psychology Review, 10(3), 251-296.