Were you even paying attention when they mentioned weeping angels in your school? Your school didn’t have classes on Weeping angels? Maybe they should.
What a stupid school..
To summarize: Weeping angels can’t move if you’re looking at them, but when you’re NOT looking at them, either your back is turned, you blink or you’re wearing a blindfold they move RIDICULOUSLY fast, and once they get to you they’ll either snap your neck or send you back in time to feed of the energy of everything you never got to do.