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Lesson 6 of 14

The job decides which test matters

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6 min

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Which material fits which job? The job decides.

Job: lamp flex, the cord of a lamp. Three materials to try: copper, pencil core, glass.
Step 1 of 3
  1. Job: lamp flex, the cord of a lamp. Three materials to try: copper, pencil core, glass.
  2. The job needs two things: carries the loop (the circuit), and draws into wire.
  3. Copper passes both. It fits the job.

The rule

A property is a quality of a material, such as shine.

Start with the job. The right material passes both properties the job needs.

Three jobs, and what each one needs
The jobWhat it needs
Wire in a lamp's flexCarries the loop, and draws thin
A bell for the school gateRings on, and survives a blow
Foil to wrap foodBeats out thin, and can be heated

The pencil core carries the loop too. But it snaps at a tap. So it fits a pencil, not a lamp's flex.

Now try it. Read the job. Tap the material that fits.

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