The Mercator tool
Almost every classroom in America has a Mercator map on it's wall:
This is the map that has been used for hundreds of years but it distorts our view of the world. It distorts the size of different countries. The farther towards the poles you move on the map, the more distortion there is. It's a fairly abstract idea (unless you've been to space).
So, how do we get this idea across to students in a concrete way? Here's how: The True Size Of
The True Size Of is a website that makes the size of land masses and how they compare to each other very clear. Search for a country, it highlights, and you can then drag that country and lay it on any other country. As the highlighted country is dragged over the map, its size changes so land mass can be compared visually.
It's a nifty little website that could be used in almost any classroom, at any age to start discussions about comparing sizes, maps vs. globes, World Geography, or even perception.