Norse Mythology by Neil Gaiman
In my experience you either learned about Norse Mythology by some independent means, or through comic books and pop culture. School had the Greek and Egyptian gods covered but I learned more about the Norse gods from the Marvel movies and Final Fantasy 2...which is really Final Fantasy 4...or something.
Before Odin was the All-Father for me, he was an optional boss that--when bested--would be a summon-able ally. He had one attack. One attack that would completely murdered your entire party in one hit. If you couldn't bring his hitpoints down to zero in time you were dead. Odin was the first in a long line of badass 8-bit bosses.
Neil Gaiman's Norse Mythology was my education into the myths of the Germanic and Viking people. Going into this book I knew it was going to be good. This was not Gaiman's first trip into mythological worlds. It's sorta his wheelhouse--between The Sandman, American Gods and others that I've just not read yet. And the audio version is read by him, which was delightful. I'm going to stereotype the British now, but hearing a Brit read anything instantly whisks me away to some sort of magical Harry Potter world, even when the book being read isn't Harry Potter.
Norse Mythology is going right onto my Reading List along with a few other Neil Garmin must-reads. If you've never read anything by him--either because you're from the past, or you're too hipster douchebag for anyone successful--then I suggest you get with the times, man, or change your ways and pick up this book.