Primary 2 maths · Measurement & time · About 8 minutes
Measure and compare liquid volume in litres
Read the liquid level, then say the unit.
Start the interactive lesson →Practise: Water-bottle station
What you will learn
- Measure and compare liquid volume in litres
Models used: number sentences, stories, bar models.
Before you start
Compare how much liquid containers hold
Two jugs hold 2 litres and 3 litres. Which holds more?
Both bars use the same scale. Compare their lengths and read the names beside them.
Read the unit with each number. Both measurements use the same unit, so their numbers can be compared.
Both bars use the same scale. Compare their lengths and read the names beside them.
3 litres is the greater measurement. The longer bar represents the larger amount, not a drawing of the object’s shape.
3 > 2
Both bars use the same scale. Compare their lengths and read the names beside them.
A litre measures liquid volume. It tells us how much liquid is in the container, not how tall the container looks.
3 − 2 = 1 litres
What did the picture help us see?
A litre measures liquid volume. It tells us how much liquid is in the container, not how tall the container looks.
Worked example: A new example, together
One jug measures 7 litres and another 14 litres. What is the difference?
Both bars use the same scale. Compare their lengths and read the names beside them.
Read the liquid level, then say the unit.
Comparing measurements requires matching the amount and unit.
Both bars use the same scale. Compare their lengths and read the names beside them.
Both measurements use the same unit.
One jug measures 7 litres and another 14 litres. What is the difference?
7 litres
Both bars use the same scale. Compare their lengths and read the names beside them.
14 − 7 = 7.
Both bars use the same scale. Compare their lengths and read the names beside them.
The difference is 7 litres.
Both bars use the same scale. Compare their lengths and read the names beside them.
Check the result against the question we started with.
Re-read the labels and unit before comparing the numbers.
We found 7 litres. Comparing measurements requires matching the amount and unit.
Common mistakes to discuss
- Comparing numbers across different units. Change both amounts to the same unit before comparing. 700 g is less than 1 kg, although 700 is the larger number.
Check your understanding
- Measure and compare liquid volume in litres
- read a liquid measurement
- check the answer against the original quantities and units
Explain your reasoning to an adult, then try a fresh question in the interactive lesson. A result from one attempt is not proof of lasting mastery.
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