Doubt

So, yesterday I learned something that contradicts the entire foundation of my American education! There are only five continents!
This means that I can no longer sing the continents' song to the tune of Frere Jacques! "North America, South America, Europe-Asia-Africa, Europe-Asia-Africa! Don't forget Australia; don't forget Antarctica! These are the continents! These are the continents!"
WRONG!
The continents include the following: AMERICA (no North or South, just America), AFRICA, OCEANIA (the fancy name for Australia), ANTARCTICA, and EURASIA!!!!!
A continent is apparently a landmass surrounded entirely by water.
My mind is blown! I no longer know what to believe! Does two plus two really equal four? I'm beginning to doubt other aspects of my childhood education. Can I not trust the education given to me? What am I to believe?