Cognitive Load Theory

The mind's workbench is small. At any moment you can hold about four things on it — not forty, not fourteen. Every teacher, manager, and parent who ignores this number is defeated by it.

Feel it yourself. Memorize a nine-digit phone number while someone explains a recipe. One of the two will fall off the bench; usually both. It is not a character flaw. It is the furniture.

Two practical consequences. First, learning: new material must arrive in chunks small enough to fit, and each chunk must become automatic — packed into long-term storage — before the bench can host the next. Second, design: every form, manual, meeting, and slide you inflict on others is competing for four slots. Whatever does not fit is not resisted; it simply never existed.

So respect the bench. One thing at a time is not a slogan for the slow. It is an accurate description of the hardware — yours and everyone else's.