I do not believe there is any such thing as "useless" knowledge and I do dislike the word relevent because it is such a personal word that when applied to a universal system has no meaning at all. As for folk, I learned quite a lot of it, in the broad sense of the word, although I might not have known what it was at the time. As for the Real world, well, I have no idea what that means..school was very real and valuable to me.