A broken mirror means seven years of bad luck. Spooky events are more likely to happen on Friday the 13th. A black cat is a sign of trouble to come. Knock on wood if you don't want something you've said to come back to haunt you. These are common superstitions. But where did they come from, and are any of them true? In Superstitions, part of Full Tilt's Origins: Urban Legends series, readers will explore the history of these beliefs. Presented through stories and timelines and filled with fun facts and vocabulary words, students will learn new ways to think about many ideas and phrases we take for granted.