Measurement
Year 3 measurement is about reading scales and comparing real amounts. Children measure length, mass and capacity by reading a ruler, a set of weighing scales and a measuring jug, lining up carefully with the marks and working out the values that fall in between. From there they compare those measures and add and subtract them.
Practise Measurement
Have a guess, even if you're not sure. Get one wrong and we'll show you why, so every miss is a chance to learn.
Timed practice
The same practice, just with a gentle clock. Pick a length and see how many you can answer.
Good to know
Units that go together
Each card shows a swap: how many small units fit inside one bigger one.
For grown-ups
Much of this year rests on the units that swap into one another: 10 mm in a centimetre, 100 cm in a metre, 1000 g in a kilogram and 1000 ml in a litre. Once a child can turn 1 m 5 cm into 105 cm, they can fairly compare, add and subtract lengths, masses and capacities without the units getting tangled. Reading a scale accurately is also a skill that carries straight into science, and the habit of converting before you calculate is the foundation for the decimal measures and conversions that come in later years.
What is in this topic
- Reading a ruler for length
- Reading weighing scales for mass
- Reading a measuring jug for capacity
- Comparing measures
- Adding and subtracting measures
How to help at home
Measurement clicks when it is real and hands-on, so reach for a ruler, the kitchen scales and a measuring jug rather than the worksheet.
- Read scales together on real instruments. Find the small marks between the numbers on a ruler, scale or jug, and count them up one by one so a mark is never just guessed.
- Practise the swaps both ways. There are 100 cm in 1 m, so a piece of string that is 1 m 20 cm long is 120 cm, and 250 cm is 2 m 50 cm.
- Line up measures before adding or subtracting. To add 1 cm and 5 mm, turn the 1 cm into 10 mm first, then 10 mm plus 5 mm is 15 mm.
- Estimate first, then check. Ask how heavy a tin of beans is or how tall a chair is, guess, then measure, so the units start to mean something.
Where children get stuck
The biggest trip-up is mixing up the swaps, because length does not behave like mass and capacity. It is tempting to think 100 mm make 1 cm to match the 100 cm in a metre, when actually only 10 mm make 1 cm. The reference card pins this down: keep saying 10 mm in a cm, 100 cm in a metre, and let the two numbers sit side by side so the difference sticks.
The other common wobble is just jamming the two numbers together, reading 1 m 5 cm as 15 cm instead of 105 cm, forgetting that the metre is worth 100 cm and not 1. Remind your child to swap the metres into centimetres first: 1 m 5 cm is 100 cm plus 5 cm, which is 105 cm, and then it can be added to or compared with any other length in centimetres without the units getting tangled.