Map projections — Geography, 11–13
How a round Earth is shown on a flat map, and why every map changes something. Geography, 11–13 years.
A flat map is a choice
Earth is almost round, but a map is flat. When we spread the surface onto paper or a screen, shapes, distances, directions or areas must change somewhere. A map projection is the particular way a map-maker chooses to make those changes.
Why do we need them?
People needed maps for sailing, travelling, measuring land and comparing places, but they could not press a globe flat without wrinkles or tears. Different jobs need different priorities: a navigator may protect directions, while a map of countries may protect area. No projection is perfect for everything.
A country that looks too large
On a common world map, Greenland looks nearly as wide as Africa. Compare their real areas: Greenland is about 2.2 million km², while Africa is about 30.4 million km². Africa is therefore about fourteen times larger. The map has stretched places near the poles, so appearance is misleading.
The map is not lying
A reasonable mistake is to treat the shapes and sizes on one world map as exact, because a map looks measured and precise. The real issue is not that the map is useless or dishonest; it is that it cannot show a curved surface flat without distortion. Check the projection before comparing places.
Choosing a useful map
A weather map, a subway map and a classroom world map do not need to show exactly the same things. A weather map may favour clear areas for storms, while a navigation map may favour reliable directions. When reading any map, ask what job it was designed to do.
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