Map Skills (Grade 10 NSC Matric Geography): Revision Notes

Scale

What is scale?

Scale is a fundamental concept in geography that shows us how much smaller a map is compared to the real world. Think of scale as a way of shrinking the enormous world down to fit on a piece of paper whilst keeping everything in the correct proportions. When we use maps, we need to understand exactly how much smaller the map is than reality so we can work out real distances and areas.

Maps can show different amounts of detail depending on their scale. A map showing the whole of South Africa will have less detail than a map showing just your local area. This is because we have the same amount of space on paper, but we're trying to fit different amounts of the real world onto it.

Below you can see three maps drawn to three different scales.

Maps covering large areas use a small scale, whilst maps showing small areas in great detail use a large scale.

Three ways of representing scale

Geographers use three main methods to show scale on maps: word scale, ratio scale, and line scale. Each method has its advantages and is useful in different situations.

Word scale

Word scale is the simplest way to describe how big or small a map is. It uses everyday language to explain the relationship between distances on the map and distances in the real world.

The key word to remember is "represents" - we always say one unit on the map represents a certain distance on the ground. We never say it equals that distance, because the map is obviously much smaller than the real world. The word "represents" reminds us that we're looking at a scaled-down version of reality.

Ratio scale

Ratio scale describes the relationship between map distance and ground distance using numbers. It compares one unit of measurement on the map with the same unit of measurement in the real world.

This tells us that 1 unit of measurement on the map equals 50,000 of the same units on the ground.

One of the most common ratio scales you'll encounter is 1:50,000, which is the standard scale for topographic maps. This means that every millimetre on the map represents 50,000 millimetres (which equals 50 metres) on the ground.

You can also express ratio scale as a fraction, such as $\frac{1}{100}$. This is called a representative fraction and means exactly the same thing as writing 1:100.

Line scale

Line scale shows the scale visually using a measured line with distance markings. If you look at a line scale, you can see exactly how long distances are on the map by measuring against the scale line.

The line scale shows you immediately what real-world distance any measurement on the map represents. You can use a ruler to measure distances on the map, then compare your measurement to the line scale to find the actual ground distance.

Working with measurement units

Understanding the metric system is essential when working with map scales. Here are the key relationships you need to remember:

When working with scales, it's often easier to think in terms of metres and kilometres rather than smaller units. For example, if you have a 1:50,000 scale map, you can work out that 1 centimetre on the map represents 500 metres on the ground (because 50,000 centimetres equals 500 metres).

Understanding scale relationships

There's an important relationship between scale numbers and the area they show that often confuses students:

Think about it mathematically. In the fraction $\frac{1}{1,000,000}$, you're dividing by a very large number, which gives you a very small result. This small result means the map shows things much smaller than reality, so you can fit a large area onto the page.

Conversely, $\frac{1}{10,000}$ is a much larger fraction, meaning things on the map are closer to their real size, so you can only fit a small area with lots of detail.

Remember!