World War I left a long and painful legacy. How long: Germany didn't manage to pay off its reparations payments until 2010! And how painful? Painful enough that the vindictive terms of the Versailles Treaty led to the rise of Hitler and World War II. 

In addition, hasty decisions made over the disposition of territories that made up the former Ottoman Empire left the Middle East unsettled and resentful of western interference...a dynamic that remains in place nearly 100 years later. One of the opportunities in teaching World War I, therefore, is to explore the significance of a good peace. Winning a war is only half the battle. When the war-ending treaty is not well constructed, generations down the line pay the price.