The unit most students are waiting for from the beginning of the school year: World War 1, Great Depression, World War 2. Most students will feel really comfortable with this content.
You'll see the causes of WW1, including the complex alliances between European powers and the territorial disputes that arose as a result, building on tensions that escalated in unit 6 in the scramble for imperial power. You will look at how the outcomes of the war, such as the Treaty of Versailles, led to the rise of fascism in Europe and contributed to the start of World War II.
Another important event in this unit is the Russian Revolution, when communism swept Russia and transformed it into the USSR, which set the stage for the Cold War (contextualization!).
The Great Depression caused populations to seek fast solutions to crippling economic trouble, which led to the rise of dictators. Germany took that a step further by invading neighboring countries, re-starting the conflict that was hardly ended by the Treaty of Versailles. Hello World War 2!
It closes out by looking at atrocities and genocides. This unit is overall a very bloody and full of social, political, and economic upheaval.
The essential question for this unit is: How did different ideologies impact states politically, economically, and technologically in the early 1900s?