In 1787, the Framers of the US Constitution came together to create a stronger central government. In this video, Kim discusses how the Framers compromised over the plan for the legislative branch of government, combining the Virginia Plan and New Jersey Plan to form the House of Representatives and the Senate.

During the Constitution Convention, the Framers made several compromises, including the method for counting enslaved Africans for the purposes of population (the Three-Fifths Compromise) and the end of the international slave trade.

In this video David explains what constructive and destructive interference means as well as how path length differences and pi shifts affect the interference. Created by David SantoPietro.

In this video, we introduce the concept of consumer surplus as the difference between marginal benefit and price paid. Created by Sal Khan.

Thinking about a consumption function where taxes are also a function of income (which is more realistic than constant taxes). Created by Sal Khan.

Review of the difference uses of the words contango, backwardation, contango theory and theory of normal backwardation. Created by Sal Khan.

What a trader means when they say that a market is in contango. Created by Sal Khan.

Why did Islam emerge and spread when and where it did? Why was it so rapid?

How revolutionary was the American Revolution? In this video, Kim models the historical thinking skill of continuity and change by comparing society before and after the Revolutionary War.

How much change did industrialization really bring during the Gilded Age? In this video, Kim discusses the impact of industrialization on work, migration patterns, and culture.

How much did the events of the tumultuous postwar era reshape American national identity? Kim discusses the extent to which developments like the Cold War, the Civil Rights Movement, Vietnam, and student protests of the 1960s changed core beliefs around citizenship, cultural values, and the proper US role in the world.

By convention, we define positive direction of current to be in the direction a positive charge would move. Electrons (with their negative charge) move in the opposite direction of the positive current arrow. Created by Willy McAllister.

Learn a technique for converting decimal numbers into binary numbers using just pen, paper, and calculations. Works best for small numbers, since bigger numbers require increasingly more calculations. Created by Pamela Fox.