Idea 12of 22Builds onSmaller unit, more of them
Metres, centimetres and millimetres
How many of each small unit fit in one metre?
Today you'll discover
- the length units in order
- the × 10 between neighbours
- how many cm and mm make a metre
Think firstThe length units, biggest to smallest
How many centimetres make 1 metre?
Decide first, then press Next. Count the steps between two units.
Seven boxes in a row: km, hm, dam, m, dm, cm, mm, with the rarely used ones faded. Curved arrows marked × 10 join each pair of neighbours. Then a line under the smaller boxes: 1 m = 10 dm, 100 cm, 1000 mm. The last step asks how many millimetres make a metre stick.
See the whole ideathe big idea and the key word, in one place
The big idea
1 m = 100 cm = 1000 mm: each step down the units is 10 times as many.
The three you will use most
Remember these and you can work out the rest.
- 1 m100 cm
- 1 cm10 mm
- 1 m1000 mm
Easy to get wrongDecimetres are real but rarely used. Skip them, and m to cm looks like one step; it is two: × 100.
Key word
- decimetre
- 10 cm, written dm; a real unit between the centimetre and the metre, rarely used
Ready to use it?
- Say how many cm or mm make 1 m.
- Describe how two length units are related.