__Measurement: Length__
## The standard unit for measuring length is the metre, m.
The metre is part of the metric system or ' *The International System of Units (SI)*' which was established in 1960 and is derived from the distance that light travels in a vacuum over a very small time interval - 1/299,792,458 of a second!
### 1 metre is about the height of a door handle in your house.
### Other metric units of length are derived from the metre. Common units are:
### kilometre, km = 1000 metres
### millimetre, mm = 1/1000 of a metre - about the thickness of a 5p coin.
### centimetre, cm = 10mm = 1/100 of a metre - about the width of a little fingernail.
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## In the UK we use a combination of Metric and Imperial units, which means that your child has to understand and be able to compare both types of measurement.
### Imperial units of length are miles, yards, feet and inches.
### One inch is approximately 2.5 cm - about the diameter of a 2p coin.
### One foot = 12 inches - approx 30cm - about the height of a wine bottle.
### One yard = 3 feet = 36 inches - approx 92 cm, a bit less than a metre. |