What are Units?
Units lets us know exactly what a number is refering to.
If I were to tell you that ‘I ran 100’. You wouldn’t realy know what I meant. ‘Ran 100 what…?’ You might ask. That’s where units come in, they tell us what a number refers to.
If I said ‘I ran 100 meters’… it would make a lot more sense!
A lot of units to do with length, mass and weight start with either:
milli, centi or killo
Milli means a thousandth. For example a millimeter is 1 thousandth of a meter… in other words there are 1000 millimeters in 1 meter.
Centi means a hundredth. For example a centimeter is 1 hundreth of a meter… there are 100 centimeters in a meter.
Killo means one thousand. A killometer is 1000 meters.
Units of Length
Units that measure length are quite straight forward.
A kilometer is 1000 meters.
A meter is made up of 1000 millimeters.
A meter is also made up of 100 centimeters.
A centimeter is made up of 10 millimeters.
Units of Mass
An object’s mass is how heavy it is.
A kilogram is 1000 grams.
Mass is sometimes measured in:
Stone, pounds and ounces
A stone is made up of 14 pounds.
A pound is made up of 18 ounces.
Units of Volume
An object’s volume is the space that it takes up.
We talk about the volume of 3D shapes in another lesson, these are measured in:
Liquids however are usually measured in:
Litres and millilitres
The volume of a liquid is sometimes called capacity.
A litre is made up of 1000 millilitres.
A Liquid’s volume can also be measured in pints.