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Lesson 4 of 10

A model is a tool

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7 min

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How long will your bicycle ride to school take?

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Here a signal means a traffic light.

The question: how long is the ride to school?
Step 1 of 4
  1. The question: how long is the ride to school?
  2. Keep what matters most: distance and speed.
  3. Add smaller details: a slope, two stops, a signal.
  4. Leave out what makes no difference: the colour.

The idea

Distance ÷ speed gives most of the ride time. A simple model can start with just these two.

The natural world is complex, with very many parts. Studying all of it is often impossible. So science uses models.

A model is a simplified view of a real system. A system is a set of connected parts. The model keeps what matters for one question. The model leaves out the rest, on purpose. These choices are not mistakes.

Think of the ride. Distance and speed give most of the time. A slope, two stops and a signal add a few minutes. The colour of the bicycle adds none. A simple model can leave out the colour.

More details give an answer closer to the real time. But the model gets harder to use.

Every branch of science uses models.

  • Physics: a moving car as one point.
  • Chemistry: atoms as balls joined by sticks.
  • Biology: a cell as a labelled drawing.
  • Earth science: Earth as a smooth ball with layers.

Try the lab to finish this lesson.