In this lesson, students analyze primary source documents in an effort to answer the central historical question: Who was primarily responsible for the Cold War: the United States or the Soviet Union? The teacher begins with a timeline and brief PowerPoint to set up early Cold War chronology. Students then receive 2 documents—Churchill’s “Iron Curtain” speech and the “Truman Doctrine” speech—answer guiding questions and formulating an initial (probably pro-American) hypothesis. They then corroborate this with another 2 documents—a telegram by Soviet ambassador Novikov and a critical speech by Henry Wallace—and formulate another (perhaps more sympathetic to the Soviet position) hypothesis. Students share answers and discuss as a class: which hypothesis is more believable? What further evidence would you like to see?