oldie but goodie. For those who are new to map-making, the reason Africa does not look nearly as big as it really is (and why Greenland looks so big) is because of something called "map projections", i.e. the choices that were made as to the formula for projecting a spherical earth onto a flat piece of paper. The most popular projection in use "mercator" favored an accurate representation of western europe and distorted other regions, the smaller size of Africa being one casualty. Here is more reading for those who are interested:
http://www.petersmap.com/page3.html