One way to introduce the idea might be a sort -- give people strips of paper with events, people, factoids that are at least somewhat familiar and ask them to organize them in any way they like. Compare. If no one did it chronologically, ask people to do that, then compare the chronology to the other orders. A good sort is the It's a Mystery activity in Power in our Hands, about the sudden rise of racism in Chicago post WWI. http://zinnedproject.org/materials/power-in-our-hands/