If you go here, you will see a really good infographic on the size of Africa. In many ways it gives you a good sense of just how big Africa is. It is big, of course. This is not surprising to me, since it is a major continent, but it may be for alot of people.
What I do find odd is the comparisons. Most of them compare Africa (a continent) to other countries. Africa is a big continent, especially when compared to Europe. However, it would make more sense to compare it to North America (rather than just the United States) or Asia (and not just Japan, China or India). I think North America is comparable in size to Africa and Asia. (If anything, I believe Asia would be bigger). I suspect the author wanted to emphasize how big Africa is. Fair enough. But if they want to tackle the so-called problem of immappancy, they should try a different approach.