Please know the following terms and how they apply to World War I: Central Powers, Allies, U-Boats, Lusitania, George Creel, Zimmerman Note, Committee on Public Information, Espionage Act and Sedition Act of 1918, Schenck v United States, Industrial Workers of the World, Eugene Debs, Fourteen Points, League of Nations, Treaty of Versailles.
Also, attached is the article on the Treaty of Versailles that you should understand. Pay attention to the highlighted parts. Let me know if you have any questions.