WWI (1914-1918) was the first "modern," weaponized war in world history. It resulted from a number of international intentions that had intensified during the late 19th into the early 20th centuries. We used the mnemonic device/acronym: MAIN, for Joshua to understand the causes of WWI: militarism, alliance system, imperialism, nationalism. Joshua focused on the AP skill of explaining a historical concept, development or process. We viewed maps of Europe before and after WWI. Understanding WWI is essential to understanding the Russian Revolution, WWII, revolutions in Asia and events still impacting our world today.