Explain how World War I's strain broke the Russian monarchy in the February Revolution and how the Bolsheviks seized power in the October Revolution of 1917.
Russia entered World War I as an autocracy under Tsar Nicholas II, and the war strained the country past its breaking point: catastrophic military defeats like Tannenberg (1914), millions of casualties, and severe shortages of food and fuel at home turned ordinary hardship into open desperation. In March 1917 (by the Western calendar; Russia still used an older calendar that ran about two weeks behind), bread riots broke out in the capital, Petrograd, and when the army refused orders to fire on the protesters, Tsar Nicholas II abdicated, ending three centuries of Romanov rule almost overnight. A Provisional Government took formal power, but it now shared authority uneasily with the Petrograd Soviet, a rival council of workers and soldiers -- a fragile arrangement historians call "dual power."
Vladimir Lenin, leader of the radical Bolshevik faction of Russian Marxists, returned from exile in April 1917 (transported home in a sealed train, with quiet German assistance, since Germany hoped a revolution would knock Russia out of the war). His April Theses distilled Bolshevik demands into a slogan almost impossible for war-weary Russians to resist: "Peace, Land, Bread," combined with the call for "All power to the Soviets." As the Provisional Government kept the deeply unpopular war going and stumbled through crises like the Kornilov Affair, Bolshevik support surged. In the October Revolution (November 1917 by the Western calendar), Bolshevik forces led by Lenin and Leon Trotsky seized key locations in Petrograd and stormed the Winter Palace, overthrowing the Provisional Government with comparatively little bloodshed -- for now.
Mastery looks like: They can explain how WWI's strain caused the Tsar's abdication, describe "dual power," and trace how the Bolsheviks used the April Theses' appeal to seize power in October 1917.
Common stumbles: Conflating the February and October Revolutions into one event, or missing that the Bolsheviks needed months of the Provisional Government's failures before they were positioned to seize power.