Ask what a model had to leave outside

A scientific model earns its usefulness by leaving things out. A climate model divides a continuous world into cells; a genetic model may hold an environment constant; a diagram of an atom suppresses almost everything that would make it hard to draw. Simplification lets a relationship become testable or visible.

That does not make models arbitrary cartoons. Their assumptions, predictions and performance can be examined against observations. A calm way to read any model is to ask three questions: what is represented, what is held fixed, and at what scale does the answer work? The boundary of a model is part of its meaning, not an embarrassing seam.