I had the students read about the Truman Doctrine and compare whether our new foreign policy was "A radical departure, or a continuation of existing American foreign policy, but with a new face." The students unanimously agreed it was a continuation, using their background knowledge about the Monroe Doctrine, Roosevelt Corollary, US imperialism, WWI, and WWII. "We were just protecting our interests, helping capitalism expand worldwide." What are our interests? How is that beneficial? "Trade, money, control." Wow, they know more about the world than they know.
On the more comedic side of teaching, I was curious if the students understood why the Soviet mutual protection organization was called the Warsaw Pact. A student responded "Because they see the war!" War-saw...genius.