The science of learning
Cognitive load — the limit you're designing against
Your working memory can hold only a handful of new things at any one moment. Overshoot it and nothing lands. That ceiling shapes every good lesson, whether the person who built it knows it or not.
Here is an inconvenient fact about the human mind: the part that handles new information — working memory — is tiny. It holds only a few items at a time, and it holds them for seconds. Everything you have ever learned had to pass through that narrow gate.
In the 1980s the psychologist John Sweller built a theory of instruction around this limit. If working memory is the bottleneck, then good teaching is largely about not wasting it.
Three kinds of load
Sweller split the demand a lesson places on working memory into three:
- Intrinsic load — how hard the material inherently is. You can’t remove it, but you can sequence it, breaking a complex idea into parts.
- Extraneous load — effort spent on the packaging rather than the idea: a cluttered slide, a confusing diagram, being made to read and listen to different things at once. This is pure waste, and it is everywhere.
- Germane load — the good effort, the work of actually building understanding.
The whole game is to cut extraneous load to near zero, keep intrinsic load manageable, and leave as much room as possible for the germane kind.
If the mind is busy decoding your layout, it isn’t learning your point.
What it changes
Once you see cognitive load, bad training becomes obvious. The slide crammed with text that the presenter also reads aloud. The diagram whose label is on the opposite page, so your eyes ping-pong. The tool that makes you hold six steps in your head before step one pays off. All of it spends a scarce resource on nothing.
The fixes are unglamorous and powerful. One idea at a time. Words or narration, not both. Worked examples before independent practice, so beginners see the whole path before walking it alone. Whitespace. Silence.
None of this makes the material easier — the intrinsic difficulty is still there, and it should be. It just stops you spending the learner’s tiny, precious working memory on things that were never the point.