People have devised many different systems to measure the world around them. Historically some of these were based on parts of the body - such as thumb length.There are two problems with this. Can you think what they are?
Firstly, standardisation. In our example, not everyone’s thumbs are the same size and secondly, having different units of measurement can be confusing. Even recently a Mars lander crashed into the planet’s surface due to a mix up between cms and inches. A costly mistake! Therefore in 1960 a standardised system of measurement, the Système International or SI system was launched to over come these problems.
RLO Transcript (Rich Text Format 20kb)