Read a topographic map using four-figure and six-figure grid references, measure distance with the scale, and describe direction using compass points

What this dot point is asking

This skill asks you to read a topographic map confidently: to give the grid reference of a feature, to measure a real distance using the scale, and to describe direction using compass points. These are the building blocks of every map question and they appear directly in the data-response section, so accuracy and speed matter. The central idea is that a map is a coded picture of the ground, and grid references, scale and direction are the keys that unlock it.

The answer

The grid: eastings and northings

A topographic map is covered by a grid of numbered lines. The lines running up and down the map are called eastings, and their numbers increase as you go east (to the right). The lines running across the map are called northings, and their numbers increase as you go north (up). The golden rule is to read the easting first, then the northing: "along the corridor, then up the stairs."

Four-figure grid references

A four-figure grid reference names a whole grid square. You read the easting line at the bottom-left corner of the square (two digits), then the northing line at the bottom-left corner (two digits). For example, 3247 means easting 32, northing 47. Use a four-figure reference for a large feature, such as a forest, a lake or a built-up area, where naming the square is enough.

Six-figure grid references

A six-figure grid reference pinpoints a precise spot inside a square. Imagine each square divided into ten equal parts both ways. Estimate how many tenths across (east) your point lies and add that digit to the easting, then how many tenths up (north) and add that digit to the northing. For example, a point four-tenths across and eight-tenths up square 3247 has the reference 325478 (easting 325, northing 478). Use a six-figure reference for a small, exact feature such as a single building or a road junction.

Using the scale to measure distance

The scale tells you how map distance relates to real distance. A scale of 1:50,000 means 1 cm on the map represents 50,000 cm on the ground. To find a real distance: measure the map distance in centimetres, multiply by the scale number, then convert to metres (divide by 100) or kilometres (divide by 100,000). For a curving feature such as a road, lay a piece of string or the edge of paper along it, mark the start and end, then measure the straightened length.

Describing direction

Direction is given using the compass. The four main points are north, east, south and west; the points between are north-east, south-east, south-west and north-west. North is always up the map unless an arrow says otherwise. For a more precise direction you can give a bearing, an angle measured clockwise from north in degrees, from 000 degrees (north) round to 360 degrees.

Examples in context

Example 1. Planning a route on a Singapore park-connector map. A map of the Park Connector Network at 1:25,000 lets a cyclist find the grid reference of an entrance, measure how far it is to the next rest point by laying string along the curving path, and check that the route heads, say, north-east toward the reservoir. The same three skills, reference, distance and direction, turn the map into a usable plan.

Example 2. Locating a feature for a fieldwork site. When choosing where to survey, a student can pinpoint the exact spot with a six-figure grid reference so the site can be found again, then use the scale to check it is within walking distance of school. Recording the reference also lets the data be plotted accurately later.

Try this

Q1. A feature lies in the square with easting 28 and northing 65. Give its four-figure grid reference. [1 mark]

• Cue. Easting first, then northing: 2865.

Q2. On a 1:50,000 map, a straight road measures 5 cm. Work out its real distance in kilometres. [2 marks]

• Cue. $5 \times 50{,}000 = 250{,}000$ cm; divide by 100,000 to get 2.5 km.

Q3. Two points have the same easting, but the second has a larger northing than the first. State the compass direction from the first point to the second. [1 mark]

• Cue. A larger northing means further up the map, so the direction is north.