John Dickerson explains why Ronald Reagan's presidency was so significant. John Dickerson is co-host of CBS This Morning. He was previously CBS News' Chief Washington Correspondent, Political Director and anchor of Face The Nation. Dickerson is also a contributor to Slate's Political Gabfest and to The Atlantic. During the 2016 presidential campaign, Dickerson moderated CBS News' two presidential debates. Prior to CBS, Dickerson was Slate Magazine's Chief Political correspondent and covered politics for twelve years for Time magazine.

Owing to their adaptability, their skill in communications, and their reputation for ferocity, the Mongols swept across Eurasia over the 13th and 14th centuries, quickly assembling the largest contiguous empire in world history. These non-state actors had to quickly learn how to become a state themselves.

Unexpected inflation or deflation takes wealth away from one group and gives it to another group. This video talks about the winners and losers from inflation and deflation.

Woodrow Wilson attempted to build a more peaceful world after the horrors of World War I. Created by Sal Khan.

Woodrow Wilson attempted to build a more peaceful world after the horrors of World War I. Created by Sal Khan.

Learn how to use Punnett squares to calculate probabilities of different phenotypes. Includes worked examples of dihybrid crosses. independent assortment, incomplete dominance, codominance, and multiple alleles.

World War I led to many changes at home for the United States. As international migration slowed considerably, the availability of wartime factory jobs led half a million African Americans to leave the South and move to northern and western cities for work. But the US government also stifled dissent during World War I with restrictions on freedom of speech and antiwar protest.

In 1942, the United States begins to fully engage against the Japanese and go on the offensive.

In 1942, the United States begins to fully engage against the Japanese and go on the offensive.

What would fall faster on the moon, a brick or a feather? Created by Sal Khan.

Sal provides a historical overview of the Zhou, Qin, and Han dynasties in China.

An intercepted telegram between Germany and Mexico led the United States to declare war. Created by Sal Khan.

An intercepted telegram between Germany and Mexico led the United States to declare war. Created by Sal Khan.

A primer on the Zoroastrian religion. Discussions of Zarathustra, Ahura Mazda and the Avesta.

This video discusses how economists measure the total factor productivity, capital, and human capital for an aggregate production function.

Economists have long been interested in the causes of the business cycle. In this video we define the business cycle, discuss potential reasons it exists, and explore how it may be driven by emotion. Created by Sal Khan.

Overview of how carbon is recycled through our biosphere in the carbon cycle.

The discount rate and window. Lender of last resort. Created by Sal Khan.