Reading maps and scale
A map is a scaled-down drawing of the real world. The scale tells you how many times smaller, so you can work out real distances.
You can start here straight away: you need nothing first.
Why
On the town plan of where you live, your home and your school are only a few centimetres apart. How far do you really have to cycle?
A map fits on a sheet of paper or on your screen, the real street does not. So everything on the map has been made smaller the same number of times.
If you know how many times smaller, you can turn every distance on the map back into the real distance. That number is on every good map: the scale.
See it
Slide the scale and watch the same neighbourhood grow or shrink on the map. The real distance between home and school stays the same, only the map changes.
Description of the picture
A drawn town plan with a house, a school, a park and a river. At a scale of 1:
Get it
A scale like 1:
The bigger the number after 1:
Many maps also have a scale bar: a short line with the real distance next to it. It stays right when you print the map bigger or smaller, the scale as a number does not.
A map always has a title, a key that explains the symbols, a scale and an arrow pointing north. Without a key you cannot tell what a blue line or a small black square means.
Real distance =
Worked example
On a walking map with a scale of 1:
Multiply the map distance by the scale number.
6×
25 000= 150 000 That is 150 000 cm. Divide by 100 000 to get kilometres.
150 000:
100 000= 1.5 Check: 4 cm is 1 km on this map, so 6 cm is a bit more than 1 km. That checks out.
- Answer
The church and the mill are 1.5 km apart.
Do it
Choose a level. You get a new exercise every time, checked straight away.
Pitfalls
Wrong: A map at 1:
100 000 is a large-scale map, because the number is large. What counts is the fraction 1 in 100 000: a very small ratio. Everything has been shrunk a lot.
Right: 1:
100 000 is a small scale with little detail. 1: 10 000 is a large scale with lots of detail. Wrong: 3 cm on a map at 1:
50 000 is 150 000 m. The scale number works in the same unit as your measurement. You measure in centimetres, so the result is in centimetres too.
Right: 3×
50 000= 150 000 cm, which is 1 500 m or 1.5 km. Wrong: You enlarge a map on the photocopier and the scale stays the same.
After enlarging, 1 cm on the paper stands for less real distance than before. The scale number is no longer right.
Right: Use the scale bar: it is enlarged along with the map, so it stays right.
In real life
- On the cycling junction map of your province you plan a ride and use the scale to estimate how many kilometres it will be.
- A town plan at the station shows where you are, with a red dot and a scale bar underneath.
- On a youth group outing you read on a walking map of the Ardennes how far it still is to the campsite.
- In a map app on your phone the scale bar changes when you zoom in or out.
History
Gerardus Mercator was born in 1512 in Rupelmonde, on the Scheldt. He made maps and globes, and in 1569 a famous world map. We owe him the word atlas for a book full of maps.
At the table
Take a map or a map app together and find your home and the school. First guess how far it is, then work it out with the scale. Who was closest?
A question to talk about together, for parents and children. There is no wrong answer.