World Geography · Unit 1 · Grades 6-8
Maps, Globes and Coordinates
How do you squash a round planet onto flat paper, and how do you give every spot on it an address?
Pick any place: your school, a lighthouse in Japan, a ship in the middle of the Pacific. With just two numbers, latitude and longitude, anyone in the world can find that exact spot. By the end of this page you'll be able to read those numbers. You'll also see why Greenland looks as big as Africa on many classroom maps, even though Africa is about 14 times larger.
Why Every Flat Map Stretches Something
A globe is a model of Earth shaped like a ball. It shows sizes, shapes and distances correctly, but you can't fold it into your backpack or see the whole world at once. A map is a flat drawing of all or part of Earth's surface. Maps are handy, but they have a problem.
Try this: peel an orange and press the peel flat on a table. It tears, or it stretches, or you leave gaps. A round surface just won't lie flat without changing. Mapmakers face the same problem. Their method for moving the round Earth onto a flat page is called a projection. Every projection has to distort something: size, shape, distance or direction. Mapmakers choose which one to sacrifice depending on what the map is for.
Look at Greenland (red) and Africa (gold). On the Mercator map they look like they could be close in size. In real life, Africa covers about 30.3 million square kilometers and Greenland about 2.1 million. Africa is roughly 14 times bigger!
So which map is "right"? None of them is perfect, and that's the point. A sailor might want Mercator. Someone comparing the sizes of countries wants an equal-area map. Only a globe gets everything right at once. My drawings here are simplified by hand, but the stretching you see works the same way on real maps.
The Parts of a Map
Most maps share four tools that help you read them. Here they are on a map of an island I made up.
- 1. Title
- Tells you what the map shows and sometimes the place and year. Always read it first!
- 2. Compass rose
- Shows directions. The four cardinal directions are north, south, east and west. Many maps put north at the top, but not all of them, so check the compass rose.
- 3. Scale
- Compares distance on the map with distance in real life. On this map, the length of the black bar stands for 5 kilometers on the island.
- 4. Legend (or key)
- Explains what the map's symbols and colors mean, like a square for a town or a dashed line for a road.
Try it: Use the scale to estimate how far it is from Port Kelp to Upriver along the road. (Hint: hold a scrap of paper against the bar and mark it.)
Hemispheres: Earth in Halves
Hemi means "half," so a hemisphere is half of a sphere. Geographers cut Earth in half two different ways.
- The Equator is an imaginary line around the middle of Earth, halfway between the North and South Poles. Everything north of it is the Northern Hemisphere. Everything south of it is the Southern Hemisphere.
- The Prime Meridian is an imaginary line from the North Pole to the South Pole through Greenwich, England. It splits Earth into the Eastern Hemisphere and the Western Hemisphere. On the other side of the globe, the 180° line finishes the cut.
So every place is in two hemispheres at once, one north-or-south and one east-or-west. The United States is in the Northern and Western Hemispheres. Australia is in the Southern and Eastern Hemispheres. Where is your home?
Latitude and Longitude
To give every place an exact address, geographers draw an imaginary grid over Earth. The grid is measured in degrees (°), the same unit you use for angles in math, because the lines are really angles measured from Earth's center.
Latitude: how far north or south
Latitude measures how far north or south a place is from the Equator. The Equator is 0°. The North Pole is 90°N and the South Pole is 90°S. Lines of latitude run east and west around the globe and never touch each other, so they're also called parallels. One degree of latitude is about 111 kilometers (69 miles) everywhere on Earth.
Longitude: how far east or west
Longitude measures how far east or west a place is from the Prime Meridian, which is 0°. Lines of longitude, called meridians, run from pole to pole. They go up to 180° east and 180° west, and those meet at the same line on the far side of Earth, in the Pacific Ocean. Unlike parallels, meridians squeeze together and meet at the poles.
Reading a coordinate
A coordinate is a place's latitude and longitude written together, latitude first. For example, Cairo, Egypt, is at about 30°N, 31°E. To find it:
- Start where the Equator and Prime Meridian cross (0°, 0°, in the Atlantic Ocean off West Africa).
- Go north 30 degrees for the latitude.
- Go east 31 degrees for the longitude. You've arrived on the Nile River!
For more exact addresses, each degree is split into 60 minutes (′). The Royal Observatory in Greenwich is at about 51°28′N, 0°00′.
Memory trick: Lines of latitude lie flat, like the rungs of a ladder. Lines of longitude are long, stretching from pole to pole.
How Do We Know? Finding Your Place at Sea
Today a phone can tell you its coordinates in seconds using GPS satellites. For most of history, sailors had to work them out with the sky and, later, a clock.
Latitude: look up
In the Northern Hemisphere, the North Star (Polaris) stays almost still above the North Pole. Measure how high it sits above the horizon, in degrees, and you have about your latitude. At the North Pole it's straight overhead (90°). At the Equator it sits on the horizon (0°). Sailors could also measure the sun's height at noon and look up the date in printed tables to work out latitude.
Longitude: check the time
Longitude was much harder. Earth turns 360° in about 24 hours, which is 15° every hour. So if you know the time at home and the time where you are, you can work out how far east or west you've gone. Say the sun is highest in your sky (local noon), and a clock still set to Greenwich time reads 2 p.m. You're 2 hours behind Greenwich, so you're 2 × 15° = 30° west.
The trouble was that 1700s clocks used swinging pendulums, and those couldn't keep good time on a rolling ship. Mistakes were deadly. In 1707, five British warships struck the rocks off the Isles of Scilly. Four of them sank, and more than 1,400 sailors died. In 1714, Britain's Longitude Act offered up to £20,000 to anyone who could find longitude at sea to within half a degree.
A self-taught clockmaker named John Harrison spent decades on the problem. His fourth sea clock, H4, finished in 1759, looks like a large pocket watch. On a test voyage from England to Jamaica in 1761-1762, it lost only about 5 seconds. Even so, the officials in charge made him go through another trial, to Barbados in 1764. You can see H4 today at the Royal Observatory in Greenwich.
Did You Know?
GPS puts 0° in a different spot
Visitors at Greenwich love standing on the Prime Meridian line. But GPS uses a slightly different reference, so a phone shows 0° longitude about 102 meters (334 feet) east of the markers.
Source: NOAA Ocean Service
Meridians close in
At the Equator, one degree of longitude is about 111 kilometers wide. At 60°N, roughly the latitude of southern Alaska and Norway's capital Oslo, it shrinks to about 56 kilometers, because meridians squeeze together toward the poles.
Source: NOAA Ocean Service
Zero degrees won by a vote
At the International Meridian Conference in Washington, D.C., in October 1884, 25 nations voted on where 0° longitude should go. Greenwich won 22 to 1. San Domingo voted no, and France and Brazil didn't vote either way.
Source: conference proceedings (1884)
H4 ticks five times a second
Harrison's H4 has a fast-beating balance that ticks five times every second. That helped it keep steady time even when a ship was pitching in waves.
Source: Royal Museums Greenwich
Game: Find the Coordinates
You're the navigator. Each round you get a coordinate. Your marker starts at 0°, 0°, where the Equator and Prime Meridian cross. Steer to it on the map and drop anchor. Every target is a real city, rounded to the nearest 5 degrees. Get close and you'll find out which city you've reached!
Click the map, then use the arrow keys to move your marker 5 degrees at a time. Press Enter or Space to drop anchor. You can also tap the map. Up is north, right is east.
On a phone, the arrow buttons are the easiest way to play.
Get ready…
Round 1 of 6 · Score 0 · Best 0
Your marker: 0°, 0°
How scoring works
Each round is worth up to 100 points. You lose 10 points for every 5-degree step your marker is away from the target, counting north-south and east-west steps separately. For example, 5° too far north and 10° too far west is 3 steps, so you get 70 points. A perfect game is 600. Your best score is saved only in this browser.
Quiz: Maps, Globes and Coordinates
Ten questions. Choose one answer for each, then check your score. You can try as many times as you like.
Talk About It
- Most classroom world maps use projections that make places near the poles look bigger. How might that change how people think about countries near the Equator?
- If you could design a map of your neighborhood for a new student, what would you put in the legend?
- Sailors once risked their lives because they couldn't find longitude. What do we depend on GPS for today, and what could go wrong if it stopped working?
- Why do you think so many countries agreed to use one Prime Meridian in 1884? What would happen if every country used its own zero line?
Sources
- U.S. Geological Survey, How are different map projections used? (projections and distortion, Mercator for navigation).
- National Geographic Education, Map, Hemisphere, Equator, Latitude, Longitude and Prime Meridian.
- NOAA Ocean Service, What is latitude? and What is longitude? (size of a degree, 15° per hour, the GPS offset at Greenwich).
- Reuters Graphics, The true size of Africa (areas of Africa and Greenland).
- University College Oxford, Mercator's Atlas (Mercator's 1569 world map, made for use in navigation); National Geographic Education, Gerardus Mercator.
- NASA, Navigation, from From Stargazers to Starships (finding latitude from Polaris and the sun).
- Royal Museums Greenwich, Longitude found: the story of Harrison's clocks and What made the search for longitude so important? (the 1707 Scilly disaster, the 1714 Longitude Act, H4).
- International Conference Held at Washington for the Purpose of Fixing a Prime Meridian and a Universal Day (1884), Project Gutenberg eBook #17759.
- City coordinates in the game: each city's article on Wikipedia, checked October 2026 and rounded to the nearest 5 degrees.
Credits
Written by Marco for Jugami's World Geography course. All maps, globes and diagrams are original SVG drawings made for this page. The coastlines are simplified by hand from latitude and longitude points, and the projections are calculated from the same points.