Page 25 - DESIGN & MODELING

Lesson 1: What Is Measurement?

History of Measurement

When you want to tell someone how big or how far away something is, you need a ‘common
system’ for communicating this information.

Despite what you may read in the newspaper, the length of a London bus or an area the size of
Wales or Texas are not common units of measurement, and they are not universally understood!

The US Standard system of measurement has been in use for a very long time. It involves units
such as pounds and ounces for weight, miles, yards, feet and inches for distance, and pints and
gallons for volume.

It’s not a simple or intuitive system. For example, there are 12 inches in a foot, 3 feet in a yard,
and 16 ounces in a pound. What’s more, because the units aren’t in nice easy numbers, neither
are the parts: to explain how many ounces you need in terms of pounds, you need to use
fractions.

In the UK, the invention of the metric system is often attributed to Napoleon, but that is probably
a myth. Whoever invented it, the metric system was designed to make measuring and comparing
easier. All the units are in multiples of 10: there are 10mm in 1cm, 100cm in a meter, 1000m in a
kilometer, and so on. It means that all the sums can be done as decimals.

Measurement, and the ability to determine the accuracy and precision of any given measurement,
is the basis of all science, technology and engineering. For instance, the ability to measure and
produce mass market goods that precisely reproduce specific measurements enables the
availability of inexpensive cables that reliably connect computers to printers. It also results in the
manufacture of memory devices that plug easily into sockets of a motherboard. In this activity,
students learn how to determine the certainty of their measurements, and then use the
measurements to compute various variables. The statistics used in this activity form the basis for
applications used across various fields of engineering and science, from determining whether a
population has a higher rate of a certain illness, to proving that a photon can act like a particle.
For many engineers, the accuracy and precision of the measurements in their designs affects

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