The true size of Africa
Kai Krause came up with this awesome map to help in the “fight against rampant Immappancy,” i.e. insufficient geographic knowledge:
A survey with random American schoolkids let them guess the population and land area of their country. Not entirely unexpected, but still rather unsettling, the majority chose “1-2″ billion” and “largest in the world,” respectively.
Even with Asian and European college students, geographical estimates were often off by factors of 2-3. This is partly due to the highly distorted nature of the predominantly used mapping projections (such as Mercator).