Use multiple varied examples to map the concept’s true shape

Three different examples reveal what one example hides — the edges of the concept.

Why it works

A single example highlights certain features while hiding others that are irrelevant. When learners see only one instance, they often bind the concept to surface features of that instance rather than its defining structure. Multiple examples from different contexts force the brain to abstract the invariant principle, which is what actually enables transfer to new situations.

How to do it

1. For any new concept, seek or generate at least three examples from different domains.
2. For each example, explicitly ask: which features are essential to the concept, and which are incidental?
3. Look for a near-miss example — something that almost fits but doesn’t — to sharpen the boundary.
4. Write a one-sentence definition that covers all your examples and excludes the near-miss.

Evidence

Variability in examples is a well-established principle in cognitive and educational psychology. Studies on category learning show that varied training instances produce better transfer than identical ones, even when total exposure time is equal. (observational)

The benefit of variability depends on sufficient initial understanding — too much variation too early can overload novices.

Sources

• Kornell & Bjork (2008), learning concepts and categories, Psychological Science

Common mistake

Accepting the first example that "clicks" as complete understanding, then applying the concept incorrectly to novel situations because the irrelevant features of the example were mistaken for the rule.