Before measuring something, you need to know what unit to use. You can do this by estimating its approximate size. For measures such as speed you will use a formula.
The commonly used metric units of length include:
The commonly used metric units of mass include:
The commonly used metric units of capacity include:
To find a suitable unit to measure something in, you should first estimate how big it is. So, for example, do you think it's better to measure the distance between London and Manchester in metres or kilometres, or should the length of an insect be measured in metres or millimetres?
Imagine the length of the objects you are estimating or imagine measuring them in relation to other objects. For example:
Q1. Which unit of measurement (\({km}\), \({m}\), \({cm}\)or\({mm}\)) would you use for the following?
a) the length of the span of your hand
b) the length of a football pitch
c) the thickness of a notebook
d) the distance from London to Manchester
Q2.
a) Is the height of a tall man likely to be \({90}~{cm}\), \({180}~{cm}\) or \({360}~{cm}\)?
b) Is the weight of a bag of sugar about \({1}~{kg}\), \({10}~{kg}\) or \({50}~{kg}\)?
c) Does a kettle hold roughly \({200}~{ml}\), \({1}~{l}\) or \({10}~{l}\) of liquid?
A1.
a) \({cm}\)
b) \({m}\)
c) \({mm}\)
d) \({km}\)
A2.
a) \({180}~{cm}\)
b) \({1}~{kg}\)
c) \({1}~{l}\)