I feel like World War II is one of those subjects that is nearly impossible to cover in school. There is just so much happening in so many different places over such a long period of time, it is no wonder that so many details get left out. Even if you try to do your own research, the sheer amount of information out there can be overwhelming and you may not know where to start.
Fortunately, some of the good folks on Reddit are here to help you out and share some lesser known facts. They don't cover everything here, obviously, but it is a good place to start.