How do we measure objects?
Length is how long or tall something is. It is usually measured in millimetres (mm), centimetres (cm) or metres (m).
If you take a look at a ruler you will see lots of tiny lines. The smallest lines are millimetres and the bigger lines are centimetres (cm).
There are 10 mm in 1 cm.
That means:
- 10 mm = 1 cm
- 20 mm = 2 cm
- 90 mm = 9 cm
- 100 mm = 10 cm
Most rulers only measure objects up to 30 cm.
When we measure big objects we normally measure in metres (m).
We can use a tape measure to measure larger objects.
There are 100 cm in 1 m.
That means:
- 100 cm = 1 m
- 200 cm = 2 m
- 900 cm = 9 m
- 1000 cm =10 m
Example 1:
Which of these measurements is the longest?
3 cm, 9 m, 20 cm, 14 m
The answer is 14 m (14 m is the same as 1400 cm).
Example 2:
Which of these measurements is the shortest?
13 mm, 24 cm, 50 mm, 8 cm
The answer is 50 mm (50 mm is the same as 5 cm).
