Subject: Geography

Topic: Where are we?--- Basic Map Reading Skills for Secondary 2 students

Prepared by:

Lai Ka Man, Jenny99558401LED 1/4

Introduction :

This presentation is mainly for Secondary 2 students, who have obtained a certain level of map reading skills before, such as thebasic directions (North, East South, West), and map symbols.These slides are best accompanied by the use of a map readingexercise book and it is mainly for lecture.

Objectives :Map is an useful tool for us to locate the places we don’t know. It can also tell us the features of the place, such as the relief, land use and settlements.. In this presentation, we will learn the way of using the Grid System, Scale and Direction, so that we can apply them when traveling and hiking…etc.

Part one --

To locate places on a large-scale map, we use the Grid System. This consists of vertical lines called Eastings and horizontal lines called Northings.

Eastings

Northings

Grid Square and Grid Reference

When we read a map and grid reference lines, we always look at the Eastings first(the vertical lines), from left to right.Then we look at the Northings (the horizontal lines), from the bottom to the top.

Eastings

Read Easting FIRST

80 81

90

91

From left to right

From bottom to the topNorthings

We try to locate a place by looking in the the Eastings and Northings

80 81

90

91 How can we express the location of the blue dot in the grid reference?First, we look at the Easting, it’s between“80” and “81”. Since we read Easting from left to right, therefore, the blue dot is in the “80” area.Then, we read the Northings, from the bottom to the top. The blue dot is between

“90” and “91”, but it still has not reached the “91” line, so we say that the dot is in the “90” area”. Hence, we can have a conclusion that the grid square of the blue dot is “8090”.

Grid Square of the blue dot: 8090

Sometimes, when indicating some features, the grid square is not accurate and precise enough. As you can see from the grid squarebelow, there are two dots in the same grid square (1082), we cannot distinguish the actual locations of the dots. In this case, we have to usea more precise method called Grid Reference.

10 11

82

83

10 11

82

83

Grid Reference Grid Square

In a Grid Reference, we subdivide the Eastings and Northings into 10 more units. The reading method is the same as Grid Square. However, we add one more figure after the Easting and Northing.For example, the Easting of the blue

10 11

50

49 1 2 3 4 5 6 7 8 9

987654321

dot below is 106, and its Northing is 497. Therefore, we say that the Grid Reference of the blue dot is 106497. Remember, Grid Reference is always a 6-figure unit.

Now, let’s have an example on grid square. In the following map, what is the grid square of Science Center (the red circle)?

23 24 25 26 27

64

63

62

CUHK

61

Hint: read the easting first.

The science Center is atthe east of Easting 25, and it is north of Northing 63.So, can you get the answer?

Yes, its grid square is 2563

Part 2--

We know that the map shows the images which is much smaller than the actual ground. How can we know its actual size? We can know it from Scale.

There are three types of scale:(1) Statement Scale

(2) Representative Fraction (R.F.)

(3) Linear Scale

Scale

(1) Statement Scale

In this kind of scale, it is expressed in the form of words.For example, if 1 cm on the map represents 1000 km on the

ground, then, in Statement Scale, we will express as…

Here, 1 cm is the length on the map, and 1000 km is the actual distance (length) on the ground.

That simple? Yes! Now we move on to the second kind of scale--Representative Fraction

1cm to 1000 km

(2) Representative Fraction

We have the same way of expressing the actual distance on the ground as Statement Scale, except that we don’t use words but express as... 1:20000

1:20000 carries that meaning that “1 cm to 20000 cm” or

Here, “1” represents the length on the map, while “20000” represents the actual distance on the ground.

If you see the scale is: “1:15000”, same as the above example, it means 1 cm = 15000 cm --- 1 cm on the map equals to 15000 cm on the ground .

“1 cm = 20000 cm ”.

(3) Linear Scale

In Linear Scale, we can measure the distance directly with the scale provided on the map.

0 1000 m500 meters

In the above scale, we can see that 1 cm on the ruler is equal to500 m on the scale. Let say, if we have measured a line on the map is 37 cm long, according to the scale, it is:

37 (the line on the map)x500 m (the scale)= 18500 m (actualdistance on the ground)

Let’s have one more example. This time there is a line on the mapwhich is 15 cm long. The scale is still 1 cm for 500 m .What is the actual distance on the ground?

Since scale is expressed in fraction. Therefore, the larger the denominator, the smaller the scale. For example,

1 is larger than 1 20000 50000

Larger scale map shows greater details of the ground but covers a smaller area. Smaller scale map covers a greater area but less details

A large scale map A small scale map

CUHKCUHK

15 (the line on the map)x 500 m (the scale)

= 7500 m

Conversion of scaleScale can be changed from one to another, for example, from Representative Fraction to statement scale of cm and km.

1: 20000 (note that 1 km = 100 000 cm) 20 000 100 000

1

51 cm to

1 cm to 1 5

OR

100 000 20 000cm to 1 km

= =5 cm to 1 km

5

1

km

From Representative Fraction to Linear scale

0 2000 m 200 m

Step 1 : change the R.F. into a statement scale. 1: 20 000

Step 2 : calculate the required length of the line. 1 cm to 200 mtherefore : to measure 2 km, the length of the line = (2 / 200) cm = 10 cm

10 cm

1 cm to 20 000 cm1 cm to 200 m1 cm to 0.2 km

Part three --

Direction refers to the relative position between two points measures with a compass and expressed in terms of compassreadings.Direction and distance together tell us the exact position of an object or a place from a point of observation. The direction of an object can be expressed in three ways.

(1) Compass Point

(2) Compass Bearing

(3) Angular Bearing

Directions

(1) Compass Point

N

E

S

W

NNENE

ENE

ESESE

SSESSWSW

WSW

WNW

NW

NNW

0º

90 º

180 º

270 º

45º

135º225º

315º

There are 4 main points, south, east, south, west and subdivideinto 12 more points. There are a total of 16 points as shown below.

(2) Compass Bearing

N

E

S

W

To give more accurate direction, compass bearing is used. It is shown by both the directional points (N,E,S and W) and degree. The compass is divided into 4 parts. The directions is read either from the North or the South, but not at the East and West. Therefore, compass bearing can never be greater than 90 º. This is one of the characteristics of compass bearing.

S45ºE

How to determine whether we should use“N” or “S”? It depends on the point we measure is closer to N or S. In the figure onthe left, the point we measure is closer tothe South, so we start from the South and have the compass bearing “S45 º E”.

Let’s have some more examples...

N

E

S

W

N

E

S

W

N

E

S

W

N45ºE

S45 ºW

N45 ºWRemember, Compass Bearing never starts with “E” or “W” !

N

E

S

W

(3) Angular BearingAngular Bearing shows direction by degrees only. The angleis measured from the north arrow clockwise. In this kind of bearing, the smallest is 0 º and the largest is 360 º.

360 º

Here is one more example.N

E

S

225º

ExercisesAfter learning the three map reading skills, let’s try to do someexercises. Choose the correct answer and press on the button.

10 11

82

83

10 11

82

83

In the following figures, which one is the grid square?

Figure 1 Figure 2

C. Figure 2

D. All of the above

A. Figure 1

B. None of the above

After you have pressed the button, please move the mouse and make its pointer to appear before you press the mouse again.

What is the grid square of the orange dot and green dot respectively?

10 12

82

84

11

83

A. orange : 8411 green: 8310

B. orange: 1082 green: 1083

C. orange: 1083 green: 1082

D. orange: 8311 green: 8211

10 11

1 2 3 4 5 6 7 8 9

987654321

What is the grid reference of South Bank? (Indicated by theblue dot)

A. 457103

B. 103467

C. 103457

D. 467103

45

46

In the followings, which one is the Representative Fraction?

A. 1 cm to 1 000 m

B.

C. 1: 15 000

0 2 km1

In the followings, which one is the Linear scale?

A. 1 cm to 1 000 m

B.

C. 1: 15 000

0 2 km1

If we change the RF to Statement Scale, which one is the correct answer?

1: 50 000

A. 50 000 m

B. 500 km

C. 500 m

D. 5000 cm

A

B

The direction of Point A from Point B is...N

A. Northwest

B. Southeast

C. West

D. South

The Compass Bearing of Point X from Point Y is...A. N45º E

B. S45º N

C. S45º W

D. W45º SX

YN

N

END

Sorry, please try again!