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 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 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.

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.

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.

Here's a preview of how AC analysis is going to work. To get ready we need to review some of the ideas from trig and complex numbers. Created by Willy McAllister.

We break a sinusoidal input voltage into two complex exponentials. Using superposition, we can recover the complex output signals and reassemble them into a real sinusoidal output voltage. Created by Willy McAllister.

In this video David quickly explains each charge and circuit concept and does a sample question for each one. Created by David SantoPietro.

In this video David rapidly explains all the concepts in 1D motion and also quickly solves a sample problem for each concept. Keep an eye on the side scroll see how far along you've made it in the review video. Created by David SantoPietro.

In this video David quickly explains each 2D motion concept and does a quick example problem for each concept. Keep an eye on the scroll to the right to see where you are in the review. Created by David SantoPietro.

In this video David explains each concept for centripetal motion and solves an example problem for each concept. Created by David SantoPietro.

In this video David explains the concepts in Work and Energy and does an example problem for each concept. Link for document: https://www.dropbox.com/s/t1w6xlnkozzel17/Energy%20review.pdf?dl=0. Created by David SantoPietro.

In this video David quickly explains each concept behind Forces and Newton's Laws and does a sample problem for each concept. Keep an eye on the scroll to the right to see how far along you've made it in the review. Created by David SantoPietro.

In this video David quickly reviews the momentum and impulse topics on the AP Physics 1 exam and solves an example problem for each concept. Created by David SantoPietro.