Look at almost any world map on a classroom wall and Greenland will appear to be about the size of Africa. It is not close. Africa covers roughly thirty million square kilometres and Greenland a little over two million — about fourteen times larger, on a picture where they look like neighbours.
This is not an error. The map was drawn in the sixteenth century for sailors, and it does one thing superbly: it keeps angles honest. A compass bearing drawn as a straight line on that map is a real bearing you can steer. To buy that, the projection has to stretch the world sideways as it approaches the poles, and stretch it more the further north or south you go. Greenland sits very far north. Africa sits on the equator, where the stretching is almost nothing.
So the map is not lying. It is answering a different question from the one most readers ask it. A sailor reads it for direction and gets the truth. A pupil reads it for area and gets nonsense — and nothing on the paper warns them, because the map was never claiming to answer that.
Every diagram carries the same quiet condition. A picture is drawn to be accurate about something, and whatever it was not built to preserve, it will quietly distort. The only safe habit is to ask, before reading anything off a figure, which of its features are reliable and which are merely decoration.