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Watch: Estimating and measuring

Fin and Snoot calculate the length of their new cars, using feet, centimeters and meters.

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A girl sat at a table using a ruler and pencil to draw a line on a piece of paper.

How can we measure length or height?

We can measure lengths or heights in different units.

  • An insect might be measured in millimetres (mm).
  • A book might be measured in centimetres (cm).
  • A playground might be measured in metres (m).
  • The distance to the shops might be measured in kilometres (km).

We can solve problems of length and height if we know the different units and how they are related.

A girl sat at a table using a ruler and pencil to draw a line on a piece of paper.
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Example 1

Five children have the following heights:

ChildrenHeight
Noah96 cm
Dessie90 cm
Layla120 cm
Carley115 cm
Bilal106 cm
Five children with their names beneath. From left to right Noah, Dessie, Layla, Carley, Bilal

The children are all standing behind a wall which is 1 metre high. Whose head can be seen above the wall?

The measurement for the height of the wall is in metres, but the measurements for each child's height is in centimetres. So we need to convert the height of the wall from metres into centimetres.

1 metre = 100 cm

Look through the table again to see who is taller than 100 cm.

So, Layla, Carley and Bilal can be seen over the wall.

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Example 2

The children's eyes are 10 cm below the top of their heads. The eye heights of the five children are shown in the table below:

ChildrenEye height
Noah86 cm
Dessie80 cm
Layla110 cm
Carley105 cm
Bilal96 cm

Which of the children can see over the wall?

Remember the wall is 1 metre or 100 cm high. Look through the table above to see whose eyes are above this measurement.

You can see that Carley and Layla have measurements for eye height greater than 100 cm, so they can see over the wall.

Two girls smiling as they look over a brown brick wall.
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Top tip

Convert all lengths into the same units to make the problem easier!

  • Lengths can be in mm, cm, m or km.
  • Heights are a type of length measured upwards.
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A boy thinking with his finger on his chin.

Activity 1

My hand is 10 cm wide.

(i) How many hand-widths fit across a desk which is 120 cm wide?

(ii) How many hand-widths fit up a doorway which is 2 m high?

A boy thinking with his finger on his chin.
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Activity 2

Practise solving problems involving length and height.

Try your best to answer all of the questions.

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NEW! Play Karate Cats Maths - the winter update
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More on Measuring

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