Slide 2: The Metric System
By the eighteenth century, dozens of different units of measurement were commonly used throughout the world.
Length, for example, could be measured in feet, inches, miles, spans, cubits, hands, furlongs, palms, rods, chains, leagues, and more.
The lack of common standards led to a lot of confusion in trade between countries.
At the end of the century, the French government sought to solve this problem.
Slide 3: In 1790, the French National Assembly commissioned the Academy of Science to design a simple decimal-based system of units.
The system they devised is known as the metric system.
In 1960, the metric system was officially named the Système International d'Unités (or SI for short) and is now used in nearly every country in the world except the United States.
Slide 4: The metre was originally calculated as one ten-millionth of the distance from the North Pole to the Equator through Paris, but it is now defined in terms of wave length.
Slide 5: Common metric units of length and abbreviations
The metric units of length that are used are:
The kilometre km
The metre m
The centimetre cm
The millimetre mm
To change from one unit to another, it is simply a matter of multiplying or dividing by a power of 10.