This document discusses the difference between primary and secondary evidence that historians use to understand events in the past. It defines primary evidence as original sources created at the time of an event, such as letters, photographs, newspapers and artifacts. Secondary evidence is interpretations and analyses of primary sources, like history books, articles and textbooks. The document provides examples of various forms of primary evidence and instructs students to categorize examples as written sources, images, oral testimonies or artifacts. It emphasizes that primary sources are direct accounts while secondary sources interpret and discuss primary sources.