How to account for things when you own the building instead of renting it. Created by Sal Khan.

In this video we'll explore why regions in our scenes can go "out of focus." The region of our scene which is in focus call depth of field..

In this video David derives the mirror equation and magnification equation. Created by David SantoPietro.

Where does a buyer's demand curve come from? A rational buyer wants to get as much "bang per buck" from their consumption as possible. In economics, that's called marginal utility per dollar spent. When the price of a good decreases, the "bang per buck" on that good increases, which incentivizes consuming more of it. In this video, we derive the individual's demand curve for a good by tweaking the marginal utility per dollar spent. Created by Sal Khan.

Deriving formula for centripetal acceleration in terms of angular velocity. using linear speed formula.

Showing how a change in government spending can lead to a new equilibrium. Created by Sal Khan.

A framework for thinking about how many detectable civilizations are out there. Created by Sal Khan.

Why do we even care about the Drake Equation. Thinking about the fraction of a planet's life when a civilization might be detectable. Created by Sal Khan.

Taking a shot at estimating the number of detectable civilizations. Created by Sal Khan.

Walk through the logic of determining what kind of good has the most elastic demand in this video.

There are several factors that affect how elastic (or inelastic) the price elasticity of demand is, such as the availability of substitutes, the timeframe, the share of income, whether a good is a luxury vs. a necessity, and how narrowly the market is defined. We explore each of these in this video.

How British were the British colonies in North America in 1754? In this video, Kim discusses how the British colonies participated in political, social, cultural, and economic exchanges with Great Britain that encouraged both stronger bonds with Britain and resistance to Britain’s control.

From 1800 to 1848, the United States grew tremendously as a country, adding new territory and building national connections of business and transportation. But just twelve years later, the Civil War erupted! In this period, was the United States developing a unified national identity or a divided regional identity?

This lesson compares rational number and orders them from least to greatest using the number line. [Developmental Math playlist: Lesson 132 of 196]

This lesson demonstrates how to compare whole numbers. [Developmental Math playlist: Lesson 7 of 196]

The Paleolithic and Neolithic eras of the Stone Age. Created by Sal Khan.