Wow, I'm not a math teacher but I can tell you that 1KM is less than 1 mile. However, if the student was overreacting and asking others to revolt than he's lucky he's only getting a detention. It's one thing to correct your teacher but it's quite another one to ridicule him/her. I say this because I'm a teacher myself and I've had my curriculum questioned over stupid things such as warm up jogging and mandatory mile runs once a week. One concerning thing is how the teacher just wants the kid to accept his teaching when he acknowledges that he's wrong, that seems dictatorial to me.