SS1 Third Term Geography Lesson Note – Scales

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WEEK 2

TOPIC:  SCALES

CONTENT:

1. Meaning and Types of scale
2. Merits and demerits
3. Scale conversion.

Meaning of Map Scales

A map scale expresses the relationship between the distance or size of objects on a map and the actual distance or size of the objects on the ground. In another words, it is the ratio or relationship between measurement on the map and the actual measurement on the ground. For example, if the scale of a map is 1cm to 1km, it means that for every 1km on the ground, it is represented by 1cm on the paper.

Types of Scales

There are three types of scales namely; Statement of scale, Representative fraction or ratio scale (RF) and Linear scale

STATEMENT OF SCALE

This is a scale usually expressed as the ratio of map size to the actual size of an area in words. The statement scale can be stated in different ways. For example, one centimetre to represent two kilometres or 1cm to 1km. This means that 1cm represents the distance on map while the last figure, 1km represents the distance on the ground. Note, it is not correct to say that one centimetre is equal to one kilometre or 1cm =1km.

How to Use Statement of Scale

1. Note the two places involved
2. Measure the distance between the two places and relate it to the scale.

E.g. If a scale of a map is 2cm to 1km, what is the ground distance if the distance between the two places on the map is 10cm.

Solution:

Map distance = 10cm

Ground distance =?

Map scale = 2cm to 1km

Since 2cm = 1km

Therefore: 10cm = 10/2 X 1km = 5km.

The ground distance between the two places is 5km.

Merits of statement of scale

1. It is simple and easy to understand
2. It helps to get actual distance on ground

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