Length and centimetres · Usually met around P1
Centimetres
One end on 0; if not, take away.
How to do it
Method
One end on 0; if not, take away
From 2 to 8: 8 − 2 = 6 cm
Another way
Count the 1 cm spaces
1, 2, 3, 4, 5, 6 → 6 cm
In full
The centimetre (cm) is a unit of length; 1 cm is about the width of a fingernail. To measure with a ruler, put one end of the thing at 0: the number at the other end is how many centimetres long it is. If one end isn't at 0, take the number at that end from the number at the other end, or count how many 1 cm spaces it covers. Estimate before you measure: an eraser is about 4 cm, a pencil about 15 cm; then see how close you were.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
Which of these is about 1 cm long?
- A. A pencil
- B. A long ruler
- C. An eraser
- D. The width of a fingernail
Choose the right answer
Show the answer and working
Answer: D. The width of a fingernail
Remember a few lengths: a fingernail is about 1 cm wide, an eraser about 4 cm, a pencil about 15 cm, a long ruler about 30 cm.
Example 2
The strip doesn't start at 0. How many centimetres long is it?
Show the answer and working
Answer: 6 cm
One end is at 2 and the other at 8: 8 − 2 = 6 cm.
Example 3
A 🧊 is about 2 cm long. A bookmark is about as long as 3 of them. About how many centimetres long is the bookmark?
Show the answer and working
Answer: 6 cm
Count in 2s, 3 times: about 6 cm.
Practise it in the game →Length and centimetres · Free to start, unlimited questions, no download