Learning outcome: After this module students should be able to analyse the relationship between the units of length, mass, and time. Students should be able to measure the dimensions using the metric systems terms.

2.1 Length

Interesting fact: The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458th of a second. (https://en.wikipedia.org/wiki/Metre) In the year 1960 a group of 36 countries agreed about this definition of the meter.
Let’s remember other length units:

Unit

Abbrevation

Relation to 1 meter

1 kilometre

1 km

1 km = 1000 m

1 decimetre

1 dm

1 dm = 0.1 m

1 centimetre

1 cm

1 cm = 0.01 m

1 millimetre

1 mm

1 mm = 0.0001 m

The millimetre is the smallest unit used in the metric system. A millimetre would be used to measure something that is very small, like a seed.
The centimetre is the next smallest unit of measurement. One centimetre is roughly the width of a staple. There are 10 millimetres in one centimetre.
One meter is much longer than one centimetre. There are actually 100 centimetres in one meter. Meters are used to measure bigger objects or longer distances, such as the depth of a pool or length of a corridor. Kilometres are the longest unit of metric measurement. Kilometres are used to measure long distances, such as the distance from your house to the store or from one town to another. There are 1 000 meters in a kilometre.

Let’s take a look at the length measurement devices we use most often at home.