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Lessons in measurement uncertainty
July 3, 2007

So, you spend a good portion of your working hours making measurements, but how do you explain measurements to non-engineers, especially young ones? Here's something to try with a child.

Get a ruler. Ask your child to cut a strip of paper to a specified length, say 10 cm, using the ruler as a standard. Mark that strip with a number 1. Using strip 1 as the new reference, cut another strip to the same length and mark it number 2. Use strip 2 as a reference to cut strip 3. Now, compare all three strips to the ruler. You'll probably find that the length of strip 1 was closest in length to the ruler, followed by strip 2 and strip 3.

Conclusion: As you get further and further away from using your original measuring instrument, you lose certainty in your measurements. You can then discuss the ruler and ask how do we know that the ruler really marks off 10 cm? Well, you don't, do you?

Posted by Martin Rowe on July 3, 2007 | Comments (2)