Measuring, Estimating and Units

Hong Kong

Stage 1 - Stage 3

Lesson

When measuring the capacity of an object, it's important to use an appropriate unit of measurement. An appropriate unit will give a reasonable number that helps to convey the size of the object to others. You must make sure you are using a capacity measurement for finding the volume of an object. For example, trying to measure the calorie content of this snack wouldn't make sense in cubic centimetres.

It's important to use appropriate units of measurement so we can get a rough estimate of the size in our minds and make comparisons. For example, if I stated that an Olympic sized swimming pool contains $2500000000$2500000000 mL of water, you know it is large but it's probably hard to compare that in your mind to a pond that is $23000000$23000000 mL. It would be more appropriate to think about the size of the Olympic swimming pool in Litres, or even megalitres. Then the pool would be $2500000$2500000 L, and the pond would be $23000$23000 L. It's a little easier now to see the difference in size, so for large capacities of liquid, litres are more appropriate than millilitres.

It's also useful to be able to use small units for small objects. So measuring how much liquid you can fit in a thimble in litres wouldn't be appropriate, but millilitres then would be.

Remember that in the metric system we measure liquid capacity in litres, millilitres and so forth and we measure non-liquids in cubic metres ($m^3$`m`3), cubic centimetres ($cm^3$`c``m`3) and so forth.

When referring to the capacity of a pool, which of the following could be an appropriate unit to use? Select all correct options.

mL

AL

BML

C

What is the most appropriate unit for measuring the volume of a box ?

$mm^3$

`m``m`3A$cm^3$

`c``m`3B