"Do not go where the path may lead. Go instead where there is no path and leave a trail." I am a fan of quotes such as this, especially since I could buy cards and magnets with this quote on it from a store near my house.
Students: "But we didn't learn it last year! She didn't teach us that!" Teacher: " Oh really? Well let's ask her." *Brings last year's teacher in* "Did you teach them this?" Teacher "YES! They should remember it!