Exercise 1.
Exercise 2.

Early 1900s – World War I, booming economy, new inventions and a lot of immigrants.

1920s – Booming decade but the happy times ended with Stock Market crashing on Wall Street in 1929.

1930s – The Great Depression.

1940s – World War II.

1950s – Rock and Roll music, artists like Elvis came out.

1960s – The Civil Rights Movement, The Cold War and the Space Race.

1970s – The Vietnam War.