What are length or height?
The length of an object is the distance from one end to the other.
Height measures how tall an object is.
You can measure lengths or heights using centimetres and metres.
The height of a plant would be measured in centimetres (cm).
The height of a tree would be measured in metres (m).
Quiz: Solving problems involving height and length
Why not see how much you know about this topic already? Then work through the page and see if you can beat your score.
Measuring centimetres and metres
You can measure length and height using centimetres and metres.
A ruler is a useful tool for measuring smaller lengths.
Here is a ruler.
This is a centimetre ruler. Each division is 1 centimetre in length.
Each small division between the centimetres is \( \frac{1}{2} \) centimetre.
Now here is a metre stick.
You can use it to measure longer lengths. 1 metre is written as 1m.
There are 100cm in 1m.
A metre stick is sometimes marked with fractions, like a quarter (\( \frac{1}{4} \)), half (\( \frac{1}{2} \)) and three quarters (\( \frac{3}{4} \)) of a metre.
Here are the measurements for each in cm:
\( \frac{1}{4} \)m = 25cm
\( \frac{1}{2} \)m = 50cm
\( \frac{3}{4} \)m = 75cm
Solving problems
Understanding the different units of measurement is important when solving problems that involve length and height.
Lengths can be in centimetres or metres.
You sometimes need to convert lengths into the same units to make a problem easier!
Let's have a look at a problem.
Five children have the following heights:
Imagine these children are stood behind a wall which is 1 metre high. Whose head can be seen above the wall?
Firstly, did you notice the measurement for the height of the wall is in metres, but the measurements for each child's height is in centimetres.
So you need to convert the height of the wall from metres into centimetres.
1 metre = 100 cm
Next, look at the height of each child in the picture to see who is taller than 100cm.
Betty, Amir and Isma are taller than 100cm or 1m, so they can be seen above the wall.
Example 1
Parts of the body were once used for measuring.
If an adult stretches out their arm, the distance between the tip of their finger and their nose is about 1 metre.
Patrick used this method to measure the length of a room. He measured it as 4 arm lengths, so said it was 4 metres long.
If you used the same method to measure the room, would you have the same answer?
✓ It is likely to be a different answer because people have different arm lengths, particularly adults and children.
That is why it is more accurate to use a metre stick than parts of the body to measure.
Example 2
Some lengths are measured using fractions of a metre.
Look at these different measurements. Can you find the matching pairs?
✓ Here are the matching pairs.
More on Measuring
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