Choosing units: cm, m, g, kg, ml and litres: what children learn
Year 2 pupils learn to choose and use standard units to measure length, mass, capacity and temperature: centimetres and metres for length, grams and kilograms for mass, millilitres and litres for capacity and degrees Celsius for temperature.
In this game children decide which unit they would use to measure everyday things, such as the length of a pencil, the mass of a bag of potatoes or the water in a bath. Choosing the right unit is the first step before estimating and measuring.
This topic covers the Year 2 statutory requirement in the National Curriculum in England (Measurement): pupils should be taught to “choose and use appropriate standard units to estimate and measure length/height in any direction (m/cm); mass (kg/g); temperature (°C); capacity (litres/ml) to the nearest appropriate unit, using rulers, scales, thermometers and measuring vessels”. Year 2 pupils are usually aged 6–7.
For families following US standards, the closest Common Core standard is 2.MD.A.1, which is taught in Grade 2. US standards use customary units too; this game uses metric units only.
How to play
Sort the cards into the right groups. Tap a card, then its group. You can also drag a card, or press the number on its group. Each game has 3 rounds with no timer. Every card is checked as soon as you place it: a card in the wrong group comes back with a hint, and you get a point for each card you place right first time. For a quicker go, choose Quick quiz: 10 multiple-choice questions in 150 seconds (choose Relaxed for more time).
Step by step
- What are you measuring?. Is it how long or tall something is (length), how heavy it is (mass), how much it holds (capacity) or how hot or cold it is (temperature)?
- Small or big?. Use the smaller unit for small things and the bigger unit for big things: cm for a pencil, m for a football pitch.
- Mass: g or kg. Grams are for light things like an apple or a letter. Kilograms are for heavier things like a bag of potatoes or a person.
- Capacity and temperature. Millilitres are for small amounts such as a spoonful of medicine; litres are for bigger amounts such as a bucket of water. Temperature is measured in degrees Celsius (°C).
Worked examples
Example 1: Which unit would you use to measure the length of a pencil?
Working: A pencil is a short length.
Answer: centimetres (cm)
Example 2: Which unit would you use for the mass of a bag of potatoes?
Working: A bag of potatoes is heavy.
Answer: kilograms (kg)
Example 3: Which unit would you use for how hot the oven is?
Working: How hot something is means temperature.
Answer: degrees Celsius (°C)
Common mistakes and how to fix them
- Using a length unit for mass, such as measuring an apple in cm. Ask first: am I measuring how long, how heavy, or how much it holds?
- Choosing metres for small things. Hold up a metre stick and a ruler. Which would you use to measure a rubber?
- Mixing up capacity and mass. Capacity is how much a container holds; mass is how heavy something is.
Activities to try at home
- Look at food packets and find the units: g, kg, ml or litres.
- Bake together and measure the ingredients with scales and a jug.
- Check the weather forecast and read the temperature in °C.
Ideas for the classroom
- Set up measuring stations with rulers, metre sticks, scales, jugs and thermometers.
- Pupils estimate before measuring, then compare.
- Sort real objects by which unit you would use to measure them.
Free printable game and worksheet
The free printable starts with a game sheet, such as a colour-by-answer picture, an answer maze or a secret-code joke, followed by a worksheet. Both use the same checked questions as the online game, and the answers are on the last page. Print it, or save it as a PDF from your browser’s print menu.
Open the free printable game and worksheet
Frequently asked questions
Why litres and not 'l'?
The curriculum writes litres in full. Some packaging uses l or L as the symbol.
Are inches and pounds included?
No. The English national curriculum uses metric units in Year 2. Imperial units are met in Year 5.
Can it be played with a keyboard?
Yes. Tab to a card, press Enter to pick it up, then choose the group it belongs in.