Åk 6–9

1.2 History
Older measurement often came from different body parts, like for example, a foot (length of a foot), and ell (the length from the elbow to the little finger’s top) or a hand (the width of the hand’s four fingers).

It was practical to use this as a measuring device, but it never gave exact values. But if you compare a person’s height with the size of their feet, the result is the foot that is about a sixth of the entire body’s length.

For 4,500 years ago in Egypt, they decided to use the ell as a basis for length. It was called a cubit. The cubit could then be divided up into several smaller units.

At the end of the 1700’s, France decided that the meter should instead be the basis for lengths.  One meter was defined as a ten millionth or 1/10,000,000 of the distance between the North Pole and the equator.  This distance is 10,000 km. As the years have passed, measurement methods have been improved in order to more precisely calculate the unit of a meter.  The last calculations are based on the exact value for the speed of light.  It is nowadays defined as the distance light is carried in a vacuum in 1/299,792,458 of a second.