Chunking is the technique of breaking a large body of work, information or content into smaller, self-contained pieces that can be processed, learned or transferred one at a time. In lean it applies to work instructions, training material, changeovers, and any complex task that would otherwise overwhelm the person doing it.
Human working memory can only hold a handful of items at once. A 40-step procedure presented as one long list will be executed with errors; the same procedure presented as four groups of ten related steps is learned faster, remembered better and executed more reliably. Chunking respects how humans actually process information.
A well-written work instruction groups steps into logical sub-tasks, "prepare fixture," "load part," "run cycle," "unload and inspect", each with its own heading and a small number of clear steps underneath. Operators can absorb one chunk, execute it, and move to the next without holding the whole procedure in their head.
Effective operator training breaks new skills into small, teachable units, each practiced to competence before the next is introduced. Job Instruction Training, one of the original TWI methods, is built entirely on this principle: important steps, key points, reasons, one small chunk at a time, with practice between each.
Chunking is a small discipline with a large payoff. Whether applied to work instructions, changeovers, training or improvement projects, breaking the whole into manageable pieces makes the work more reliable, easier to learn and easier to improve.
