Measuring a classroom in centimetres would take a very long time.
Step 1: Let's Learn
Read it, or press Listen and follow the words.
For big things we use a bigger unit.
Metre is a unit of length. One metre is 100 centimetres.
Which unit to choose
Use centimetres for things you can hold. Use metres for rooms, corridors, and playgrounds.
A ruler measures centimetres. A metre stick or tape measures metres.
How the two units are tied together
One metre is exactly 100 centimetres. That is a fixed relationship, not a rough one. So a door that is 2 metres tall is also 200 centimetres tall — the same height, counted in different-sized units.
Choosing the right unit
Use centimetres for things you can hold: a crayon, a book, your hand. Use metres for things you walk past: a room, a corridor, a playground. Measuring a classroom in centimetres gives an answer like 850, which is correct but awkward. A good unit gives a number you can picture.
Carry your own measuring tools
The width of your smallest fingernail is roughly one centimetre. A big step is roughly one metre. Learn these two and you can estimate anywhere without a ruler. Check them against a real ruler once so you know how close your personal benchmarks are.
Step 2: Try It Yourself
Tap and try it out.
centimetres
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It starts at 0 and ends at 12, so it is 12 centimetres long.
Step 3: Watch an Example
One step at a time.
Watch Leo Choose a Unit
Leo needs to measure the length of the school hall.
- Step 1
He picks up a 30 cm ruler and realises it would take hundreds of turns.
Step 4: Your Turn
Practice makes it stick.
Around the School
Problem 1 of 2
Which unit would you use to measure the length of a pencil case?
The Corridor
Problem 2 of 2
Which unit would you use to measure a corridor?
Which Unit Fits?
1 of 3
How many centimetres make one metre?
2 of 3
Which unit fits a football pitch?
3 of 3
Which unit fits a paperclip?
Step 5: Quick Check
Show what you know.
Question 1 of 2
How many centimetres are in a metre?
Question 2 of 2
Which unit would you use for a bedroom wall?
What You Learned
- Centimetres suit things you can hold.
- Metres suit rooms and playgrounds.
- One metre is 100 centimetres.