How to explain metric units of mass and volume: word problems in capacity & volume to your child
31 October 2026
Metric units like litres and millilitres are used to measure how much liquid something can hold. Children often see these units on bottles or in recipes, so understanding how to work with them is very useful. Here's a simple word problem to help your child practise solving questions about capacity and volume using metric units.
Example question
A bottle holds 2 litres of water. Sarah drinks 750 millilitres. How much water is left in the bottle?
Step 1: Change 2 litres to millilitres. 1 litre = 1000 millilitres. 2 litres = 2 × 1000 = 2000 millilitres.
Step 2: Take away the water Sarah drinks. 2000 ml - 750 ml = 1250 ml.
Step 3: Change 1250 millilitres back to litres and millilitres. 1250 ml = 1 litre and 250 millilitres.
Answer: There are 1 litre and 250 millilitres of water left in the bottle.
Key insight: After working through this example, your child will see how to convert between litres and millilitres and use subtraction to solve real-life word problems. The next step is to try similar questions to build confidence with metric units of mass and volume.
