Åk 6–9

1.2 History
Development of measurement units for different situations has its roots several thousand years back in time.  During the Viking era, coins were weighed, but to determine the worth of a coin, it was also important which metal is was made of and how pure that metal was.

The Mark is our oldest weight measurement, but how much the mark weighed has changed with time.  During the Viking era for example, a mark weighed less than during the Middle Ages.  When gold or silver coins were to be weighed, it was called ”lödig”.  A “lödig” mark was about 210 g, in other words a few grams less than a ”normal” mark.

Other weight units from the Viking era is the ”skeppspund” (170 kg), ”lispund” (ca 8.5 kg), ”skålpund” (425 g), ”lod” (ca 13 g), ounce (26.3 g if it was silver and ca 28 g if it was gold to be weighed).

The first try to create a system of measurement units, which are still being used, was created in France during the French Revolution in 1789 when they wanted to break with the old by introducing new, simple, and standardized measurements.

The increase in activity in farm and manufactured products created a need for standardizes measurement units.  This applied mostly to units for length, volume and mass (weight).  Earlier different units for the measure of length, volume and mass (weight) were used, and this created problems.

During the 1790’s the mass unit kilogram was defined as a cubic meter of clean water at a certain temperature.  It was determined later that this definition was not exact and was replaced in 1889 with a standard weight (90 % platinum and 10 % iridium).