By the 1920s, a majority of the US population lived in cities rather than in rural areas. In this video, Kim explores the economic opportunities cities offered to women, migrants, and immigrants, as well as the passage of new immigration restrictions.

In this second video giving an overview of World War II, we see Germany and the Axis powers only continue to gain momentum in 1940.

In this second video giving an overview of World War II, we see Germany and the Axis powers only continue to gain momentum in 1940.

In 1941, the Axis gains further momentum with control of most of Continential Europe. Hitler decides to break pact and invade Stalin's Soviet Union. United States enters World War II after Japanese attack on Pearl Harbor.

In 1941, the Axis gains further momentum with control of most of Continential Europe. Hitler decides to break pact and invade Stalin's Soviet Union. United States enters World War II after Japanese attack on Pearl Harbor.

In 1942 we see the Axis get pushed back in North Africa and get bogged down in the Soviet Union. The tide of war turns in favor of the Allies.

In 1942 we see the Axis get pushed back in North Africa and get bogged down in the Soviet Union. The tide of war turns in favor of the Allies.

In 1943, the tide really turns in favor of the Allies in World War II. They are able to push the Axis out of N.Africa and force a surrender from Italy (along with Mussolini being deposed). The Soviets are able to start pushing the Axis out of the Soviet Union.

In 1943, the tide really turns in favor of the Allies in World War II. They are able to push the Axis out of N.Africa and force a surrender from Italy (along with Mussolini being deposed). The Soviets are able to start pushing the Axis out of the Soviet Union.

As we go into 1944, we see the allies land at Normandy, liberate France and face Germany in their last major counteroffensive at the Battle of the Bulge. On the Eastern Front, the Soviets end Siege of Leningrad and begin to push through Poland and Romania. In the south, Allies land in southern France and take Rome.

As we go into 1944, we see the allies land at Normandy, liberate France and face Germany in their last major counteroffensive at the Battle of the Bulge. On the Eastern Front, the Soviets end Siege of Leningrad and begin to push through Poland and Romania. In the south, Allies land in southern France and take Rome.

1945 marks the end of World War II. V-E Day (Victory in Europe Day) is May 8th 1945. War doesn't end in the Pacific until August of 1945 with the atomic bombing of Hiroshima and Nagasaki.

1945 marks the end of World War II. V-E Day (Victory in Europe Day) is May 8th 1945. War doesn't end in the Pacific until August of 1945 with the atomic bombing of Hiroshima and Nagasaki.

What aspects of citizenship changed with the ratification of the 19th Amendment? Created by Kimberly Kutz.

Overview of cycles of regulation, de-regulation and government in 20th century US capitalism. Created by Sal Khan.

Mrs. Rowhani's third graders learn about matter and energy by building a Spout bot with Khan Academy. Special thanks to: Santa Rita's volunteer parents, Kami Thordarson, Karen Wilson and of course Laleh Rowhani the class teacher. Created by Karl Wendt.

In this video we hack apart a bread board to create a 5 volt power distribution strip. The 5 volts comes from the center pin in the motor controller and the negative or ground comes from the ground pin on the motor controller. Created by Karl Wendt.

Vicki Lombardi's 6th grade students at Santa Rita Elementary in Los Altos School district learn how to build a Spider robot. Read more at: http://lasdilearn.blogspot.com/2013/02/third-graders-building-robots-mission.html. Created by Karl Wendt.

Solving circuits with differential equations is hard. If we limit ourselves to sinusoidal input signals, a whole new method of AC analysis emerges. Created by Willy McAllister.