What you learned at school: Herbert Hoover caused the Great Depression by being a typical Republican who sat on his hands, doing nothing, while letting people starve. Franklin D. Roosevelt rode to the rescue, creating all sorts of government welfare programs and mandating all sorts of business practices that saved America long enough for the socialist experience of WWII to give the economy the final boost it needed to come back roaring in the 1950s.
The real story: Herbert Hoover caused the Great Depression by meddling in the economy, rather than letting the free market repair itself. Franklin D. Roosevelt worsened the problem terribly, so much so that 1937 — five years into his presidency — was the worst year of the Depression. WWII definitely saved the economy at home by putting every one to work, and by kick-starting industries that were able to produce consumer goods after the war. Thankfully, Eisenhower mostly left them alone.
Here’s a video about the Hoover part of the real story: