In this video, learn about the distinction between deficits and debts, as well as the pros and cons of deficits.

Sal discusses the conditions of matrix dimensions for which addition or multiplication are defined. Created by Sal Khan.

David defines the terms amplitude and period for simple harmonic motion and shows how to find them on a graph. Created by David SantoPietro.

Explore the basics of deflation, including the definition of deflation, how the CPI changes when there is deflation, and why economists tend to be concerned when deflation occurs. Created by Sal Khan.

One of the biggest worries associated with deflation is a deflationary spiral, in which low unemployment and a decreasing price level leads to lower unemployment and an even lower price level. Created by Sal Khan.

How you can have deflation even if the money supply increases. Created by Sal Khan.

This art history video discussion examines Edgar Degas' "The Bellelli Family", 1858-67, oil on canvas (Musee d'Orsay, Paris). Degas was in his mid-twenties when he painted this canvas. It depicts from left to right, the ten-year-old Giovanna, her mother, the artist's paternal aunt Laura, her younger daughter, Giula age 7, and the Baron Gennaro Bellelli. Preperatory sketches for the painting may have been made in Florence where the family was living, the Baron had been exiled from Naples. The picture may have been completed in Paris.

This art history video discussion examines Edgar Degas' "The Dance Class" oil on canvas, 1874 (Metropolitan Museum of Art).

This art history video discussion examines Edgar Degas' "At the Races in the Countryside", 1869, oil on canvas, 36.5 x 55.9 cm / 14-3/8 x 22 inches (Museum of Fine Arts, Boston).

This art history video discussion examines Edgar Degas', "Visit to a Museum", c. 1879--90, oil on canvas, 91.8 x 68 cm / 36-1/8 x 26-3/4 inches (Museum of Fine Arts, Boston).

This art history video discussion examines Eugene Delacroix's "Scene of the Massacre at Chios": Greek families awaiting death or slavery, 1824 Salon, oil on canvas, 164" x 139" (419 cm x 354 cm) (Musee du Louvre, Paris) .

This art history video discussion examines Eugene Delacroix's "The Death of Sardanapalus", 1827, oil on canvas (Musee du Louvre, Paris).

To get a better intuition about how much a consumer values a good in a market, we think of demand as a marginal benefit curve. In this video we look at the demand curve from a marginal benefit framework. Created by Sal Khan.

Why do people hold wealth in the form of money, rather than in some other interest-earning asset? Learn about the demand for money in this video.

A real-world example of the concepts behind the AD-AS model is the inflation that the United States experienced in the late 1960s. In this video, we break down some of the events going on at the time and use the AD-AS model to see if our predictions using this model match what really happened. Created by Sal Khan.

A close reading of the beginnings of the Declaration of Independence to identify ideas of natural rights, social contract, limited government and popular sovereignty in the text.

Learn how the Preamble to the US Constitution reflects the democratic ideals of the Framers.

Ideas of natural rights, social contract, popular sovereignty, limited government and republicanism and their influence on the foundation of the United States of America.

Sociology often looks at different age cohorts. A cohort is simply a group of people, but here we're looking specifically at different age groups or generations, because these people all lived through the same certain events through a certain time that affected their lives similarly.