2. Choice of problem features

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Novices choose what to do based on surface features of a problem. Experts choose models based on the structural features of a problem.

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In other words, novices view the problem as a set of independent details and they choose one or two of them to focus on, whereas experts see the problem as a single whole.

For example:

(Exam question)

The Golden Gate bridge in San Francisco is a large suspension bridge.

golden gate bridge

The cable joining the two towers of the bridge (see illustration) can be modeled by the equation:

quadratic equation

where y is the height of the cable above the bridge deck in metres and x is the horizontal distance from the left tower in metres.

What is the distance between the towers? (Hint: both towers are the same height. The left-hand tower is at x = 0)

Student solution:

solution

You can see exactly what’s happened. This student saw the quadratic equation and immediately went and found its roots, without looking at the problem in its entirety (and realising that $y\ne 0$!).