When I was in middle school, we would have Native American Day, where the cafeteria would serve fry bread for lunch and some of the members of the local tribe would come and tell some of their stories to us. I used to think it was sort of weird (minus the fry bread, of course), but now I've come to really appreciate that we had that day. It isn't always that schools make room for the local: history, geography, culture, etc.
Maybe I used to not like the way that myths are told as facts. Whether or not people did believe myths to be facts in the past (and some still may), I think for most people myths have moved on to be symbolic rather than literal facts. They have truths even if we don't regard them as history anymore (history itself is a kind of mythology, a fact that is important not to forget--but that's another topic). And I didn't really think about that distinction, which is ironic considering that I was delving very deeply into fantasy at this time.
Mythology is a lot like fantasy, in certain ways; in fact, sometimes they blur so closely that one story could easily end up in either category. Think of it this way. Tolkien wrote The Lord of the Rings to be like a mythology for his country, and it is categorized as fantasy. So what's the difference between the two, if there is a difference?
It's odd because I think sometimes stories are categorized by things rather than theme or style. If they have time travel, they're sci-fi. If it takes place in the Southwest, it's a Western. If there are elves or goblins, it's fantasy. But mythology is reserved for old stories, for stories that have been a part of a culture for generations and generations until no one remembers how they first started. So a story that is written now or even vaguely recently will be fantasy and not mythology. If, however, it comes to have that greater applicability and become culturally widespread, it can, in some contexts, be considered mythology. The mythology of Superman, the mythology of The Great Gatsby, the mythology of the American West, the myth of Pocahontas and John Smith, the myth of how great Christopher Columbus was, whatever it is. These stories don't have to be true, per se, in order to be true in what they express as stories.
And that's what is so easy to recognize in fantasy. You read a fairy tale and you know that it's supposed to have some sort of message or moral. You read The Lord of the Rings and you find ways that it can apply to real life. Mythology does the same thing. Sure, there are going to be plenty of individual difference, but at the center of each of these groups there is a very deep similarity. I don't know why I didn't see that when I was in middle school.