A brilliant way to show how the flat world map fools us. Search for a country or tap it on the map, drag it anywhere, and it resizes to reveal its real area — move Greenland down towards the equator and watch it shrink, filled with its own flag. Drop several countries at once, try one-tap comparisons like Greenland vs Africa, switch to an equal-area map to see the truth, then print the result. A hands-on way to teach the Mercator projection, scale and how we picture the world.
The lesson that landed wasn’t a geography lesson. England had just played the Democratic Republic of the Congo in the World Cup, so I picked the DRC up off the map and slid it across the screen towards us, and it kept growing. The class had spent the week assuming it was a small country because it looked like one next to England. Once they’d seen it, the question asked itself — why is the map wrong? — and we got to map projections because they wanted the answer, not because it was next in the plan. What they worked out for themselves was the good bit: you can’t flatten a ball without breaking something, so every map is a trade-off somebody chose.
Because the Mercator projection stretches land the further it sits from the equator. Greenland covers about 2.2 million square kilometres and Africa about 30.4 million — Africa is roughly fourteen times larger. On a standard classroom world map they look about the same size, and Greenland often looks bigger.
The stretching isn’t a mistake, it’s the price of the map. Mercator drew it in 1569 for sailors, because it is the only projection where a straight line is a constant compass bearing — you could rule a course and then sail it. That property is still useful enough that almost every online map you have ever used is a version of it. What it costs is area, and the cost grows towards the poles. Greenland is far closer in size to Algeria, about 2.2 against 2.4 million square kilometres, than it is to a continent.
No flat map of the world is accurate, and no better one is coming. A sphere can’t be flattened without tearing or stretching it — an orange peel proves it in ten seconds — so every projection has to pick what it sacrifices: area, shape, distance or direction. Mercator keeps direction and gives up area. Gall–Peters keeps area and gives up shape, which is why the continents look stretched on it.
That is what the equal-area switch is for. Compare on Mercator first and let the countries balloon as they travel; then flip to the equal-area map, drag the same country again, and watch it barely change. The order matters. The reveal only works on a class that has already been fooled once.
Greenland is a continent. It is the world’s largest island, and about a fourteenth of Africa’s area.
The North Pole is land. It is sea ice floating on the Arctic Ocean with no landmass underneath, which is why no country owns it and why the map shows nothing there. The Mercator stretch makes that white band across the top look enormous, which quietly props the idea up.
Countries near the equator are small. The Democratic Republic of the Congo is about eighteen times the size of England — 2.3 million square kilometres against 130,000 — and roughly as big as Western Europe.
It works as a five-minute starter or a brain break as well as it works as a full lesson, and it is one of the few whiteboard tools where children ask to come up. I teach an international cohort, and the first thing they want is their own country picked up and moved — a country they have lived in or visited — and it is worth letting happen, because it turns a projection lesson into everyone having a reason to look at the map. Thailand is the one that surprises my class most: on the wall map it sits looking about the same size as the UK, and it is more than twice as big. It carries an assembly too: one country dragged across a big screen needs no worksheet and no preparation.
Countries fill with their own flag as you drag them, so a class can tell them apart from the back of the room. One-tap comparisons like Greenland vs Africa are ready to go, several countries can sit on the map at once, and the whole comparison prints to A4 for books or a display.
What does the True Size map show?
It shows how the flat Mercator map distorts area. Drag a country across the map and it resizes to reveal its true size compared with where it lands.
Why does Greenland look so big on maps?
The Mercator projection stretches land near the poles, so Greenland looks huge — drag it down towards the equator and it shrinks to its real size.
How do I use it?
Search for a country or tap it on the map to pick it up, then slide it anywhere; it rescales live and fills with its flag so you can compare real sizes on the whiteboard. One-tap presets like Greenland vs Africa are built in.
Can I compare two countries, like Greenland and Africa?
Yes — drag one country on top of another, or use a built-in comparison such as Greenland vs Africa, UK vs Madagascar or Russia vs Africa. You can drop several countries on the map at once.
Can I print or save the map?
Yes — the Print / PDF button pops your comparison out into a new tab as a PDF, ready to print for the board or stick in books.
Can I turn off the Mercator distortion?
Yes — switch to the equal-area (Gall–Peters) projection and sizes become true everywhere, so a dragged country barely changes. It is the perfect ‘aha’ after Mercator.
Is it free?
Yes to use — dragging and comparing countries is free for as long as you like. Exporting the comparison as a PDF spends one token, and re-exporting the same one costs nothing. Every teacher gets 20 free tokens on signing up, and Sage Teachers Pro gives you 30 a day.
What is it good for?
Teaching map projections, scale and geography, and sparking discussion about how we picture the world.
More geography for the whiteboard: GeoSpotter, GeoMystery, View from Space and Earth Explorer. For printed maps there is the Map Printer, and for how borders have moved, the Map Time Machine.
Written by a practising primary school teacher, and part of the free-to-try classroom tools on Sage Teachers. Last checked August 2026. Dragging and comparing countries is free; exporting the comparison as a PDF is free to try.