one: the word useless doesn't start with, or have an r.
two: homework was first invented as a punishment, but would be better if it were optional, just so you could use it to get a better understanding of whatever subject it was. If you already understand, you wouldn't have to do it. No, it's not useless knowledge. even if i hate homework, it prepares you for the future. Say you want to study history and make breakthroughs in science, become a world famous mathematician, or even help terraform mars when the time comes.