1km = 1000 metres.

A

B

Sometimes it’s easy to estimate a distance on a map, but we need a scale.

The scale for this map is 1:25,000

where 1cm represents 250 metres and 4cm represents 1km.

Each one of these grid boxes is 4 cm wide and

long, or 1km.

How far is it from A to B?

We can estimate a distance of 6.5

km.

A

B

But this is more difficult if the two points are like this…

Here we measure how the crow flies! Using a ruler measure the distance between the two points.

Imagine the distance on your

ruler is 8cm.

Now we need to do some

calculating.

The scale on the map was 1:25,000 or 4cm represents

1km

This means that

1 cm 0.25 km (or 250 metres)

2 cm 0.5 km (or 500 metres)

3 cm 0.75 km (or 750 metres)

4 cm 1km (or 1000 metres)

If our distance was 8cm how many kms is it?

The answer would be 2km

You could calculate this is a variety of ways…

If 4cm represents 1km, then 8cm is twice as long as 4cm, so in km it must be 2.

Or

If 1cm represents 0.25km, and you have 8cm, 8 x 0.25 would be 2km.

Your turn….

1 cm 0.25 km (or 250 metres)

2 cm 0.5 km (or 500 metres)

3 cm 0.75 km (or 750 metres)

4 cm 1km (or 1000

metres)

Using the scale 4cm represents 1km, calculate the following distances…

1 1cm

2 0.5 cm

3 5 cm

4 4 cm

5 12 cm

6 1.5 cm

7 8 cm

8 3 cm

9 6 cm

10 10 cm

You have till the end of the music.

But this method comes unstuck when you need to measure exact distance, such as a river, it’s too bendy for a ruler! Help.

Measuring Curved Line Distance Using a piece of paper.

1. Mark the location of the points on the edge of the paper.

2. Move the paper so that its edge follows the road, rail line etc

3. Use pencil marks (notches) to help you position your paper as you move it around the curve of the line.

4. Place the paper against the linear scale to work out the distance.

Another method is to use a piece of string