Geography · Lesson g05

Map Skills & Coordinates

Every spot on Earth has an address made of just two numbers. Learn the system and you can find a stable in Bavaria, a beach in Mexico, or a ship in the middle of the ocean.
A girl on a horse on a hilltop holding a paper map and a compass, looking over a wide valley with a river, mountains and a distant coast

In g04 we asked where people live and move. But "somewhere in Spain" is not much help if you want to find one particular riding school. Geographers solve this with a coordinate system, the same idea as the coordinate plane in your maths lessons, only wrapped around a ball. In this lesson you will use coordinates on the whole Earth, on a small local map, and learn to read directions and distances on both.

🌐 Big idea 1: latitude and longitude

Imagine lines drawn around the globe. Latitude lines run east-west, like rings, and measure how far north or south you are from the Equator (0° latitude), up to 90° N at the North Pole and 90° S at the South Pole. Longitude lines run from pole to pole and measure how far east or west you are from the Prime Meridian (0° longitude), which passes through Greenwich in London, up to 180°.

A location is written as two numbers with letters: Barcelona is at about 41° N, 2° E, and Mérida in Mexico is at about 21° N, 90° W. Latitude is given first.

P Equator, 0° latitude Prime Meridian, 0° longitude 30° N 30° S 60° N 60° S 30° E 30° W Point P is at 30° N, 30° E.
A globe seen from above the Equator at longitude 0°. Latitude lines are rings; longitude lines run pole to pole. Point P sits where 30° N crosses 30° E.
Maths connection: the coordinate plane (Lessons 24 to 35): latitude and longitude are an (x, y) grid wrapped round a sphere. Longitude is like x (across, east is positive, west negative) and latitude is like y (up, north is positive, south negative). Careful: geographers write latitude first, which is the opposite order to maths (x, y).
🧭 Big idea 2: grid references, compass and scale

On a local map the same idea gives a grid reference: give the number across first, then the number up ("along the corridor, then up the stairs"). The 8 compass directions are N, NE, E, SE, S, SW, W, NW, and each is 45° from the next.

Map scale works as in g01: at 1 : 50 000, 1 cm on the map is 50 000 cm = 500 m on the ground. A scale bar draws this directly.

0123456 0123456 across (east) first then up (north) Stable Riding ring Pond Hill Gate NSEW NESESWNW 0 1 2 km scale bar at 1 : 50 000
A ranch map. Each feature sits on a grid crossing, so its reference is the number across, then the number up. The scale bar is a sample for a 1 : 50 000 map (2 cm shows 1 km); it is not the scale of this grid.
Worked Examples
Worked Example 1: reading a place from its coordinates

Nairobi, Kenya, is at about 1° S, 37° E. Describe where that is.

Latitude 1° S: just south of the Equator (almost on it). Longitude 37° E: east of the Prime Meridian, well into Africa's east side. The letter matters as much as the number: 1° N would be just north of the Equator instead.

Worked Example 2: grid reference and direction

On the ranch map, give the grid reference of the Pond, and the compass direction from the Stable to the Pond.

Reference: the Pond is 4 across and 2 up, so its reference is (4, 2), across first.

Direction: the Stable is at (1, 5). Moving to (4, 2) is 3 squares east and 3 squares south. Equal east and south steps point exactly south-east.

Warm-Up
  1. Problem 1
    Name the two numbers that locate a place on Earth. For each, say what it measures and which line it is measured from.
    latitude → measured from? · longitude → measured from? →
  2. Problem 2
    Which place is closer to the Equator: one at 35° S or one at 20° N? Explain what you compared.
    ignore the letter at first, then think →
  3. Problem 3
    You stand facing north. You turn 135° clockwise. Which of the eight compass directions are you facing now?
    90° clockwise from N is …, then 45° more →
Core Problems
  1. Problem 4
    Use the ranch map. (a) Give the grid reference of the Gate. (b) Give the compass direction you would ride from the Gate to the Riding ring.
    across first, then up · count the east/west and north/south steps →
  2. Problem 5
    On a world grid with longitude as x (east positive, west negative) and latitude as y (north positive, south negative), write each city as maths coordinates (x, y). (a) Tromsø, Norway: 69° N, 19° E. (b) Santiago, Chile: 33° S, 71° W.
    x is longitude, y is latitude · watch the signs →
  3. Problem 6
    A trail on a 1 : 25 000 map measures 8 cm. How long is the real trail, in kilometres?
    cm on map → real cm → km →
  4. Problem 7 Challenge
    One degree of latitude is about 111 km on the ground. Two cities lie on the same meridian, and on a map with scale 1 : 2 000 000 they are 33.3 cm apart. (a) Find their real distance apart, in kilometres. (b) By how many degrees of latitude do the two cities differ?
    map cm → real cm → km → how many 111s? →
  5. Problem 8 Open
    On the ranch grid, design a riding trail with four stops. Write the grid reference of each stop, the compass direction of each leg, and which leg is longest. Then swap with someone and check each other's directions. There is no single right trail.
    stops · directions · longest leg →
Think like a geographer 🧭: Two numbers can name any spot on a whole planet. The same trick, one number across and one up, helps you find a square on a chessboard, a point on a graph, and a ship at sea. Whenever something needs an exact address, a coordinate system is hiding underneath.
Show answers
Problem 1
Latitude: how far north or south of the Equator (0°). Longitude: how far east or west of the Prime Meridian (0°, through Greenwich).
Problem 2
20° N is closer. Distance from the Equator is the size of the number (20 against 35); the letter only tells the side.
Problem 3
South-east (90° gives east, then 45° more gives south-east).
Problem 4a
(6, 1): 6 across, 1 up.
Problem 4b
North-west. The Ring (3, 4) is 3 west and 3 north of the Gate (6, 1). (The opposite way, Ring to Gate, would be south-east.)
Problem 5a
(19, 69).
Problem 5b
(-71, -33): west gives a negative x, south gives a negative y.
Problem 6
8 × 25 000 = 200 000 cm = 2 000 m = 2 km.
Problem 7a
33.3 × 2 000 000 = 66 600 000 cm = 666 000 m = 666 km.
Problem 7b
666 ÷ 111 = 6 degrees of latitude.
Problem 8
Open. Check that each stop reference is (across, up) with both numbers from 0 to 6, directions match the steps between stops (e.g. 3 east, 3 north is north-east), and the longest leg is identified correctly.
Next up → g06: Plate Tectonics & Hazards You can now say exactly where on Earth something is. Next we ask a different question: why do some places, such as Iceland, Japan and Mexico's Pacific coast, have earthquakes and volcanoes? The answer lies in huge moving plates under your feet, and a speed, distance and time calculation you already know.
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