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.

An independent clause is a sentence that has a subject and a verb and requires no extra information to understand. Dependent clauses, which start with subordinating conjunctions such as "while," "that," or "unless," give background information but cannot stand on their own as sentences.

Depletion gilding (dorado por oxidación). The gold-making techniques of the ancient Colombians. © Trustees of the British Museum. Created by British Museum.

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.

Describing what you see: Sculpture Henry Moore, Reclining Figure, 1951, plaster and string, 105.4 x 227.3 x 89.2 cm (Tate Britain). © The Henry Moore Foundation. This plaster was the result of a commission from the Arts Council of Great Britain for the Festival of Britain. A single bronze was cast from it. speakers: Dr. Beth Harris and Dr. Steven Zucker. Created by Beth Harris and Steven Zucker.

Describing what you see: Sculpture Henry Moore, Reclining Figure, 1951, plaster and string, 105.4 x 227.3 x 89.2 cm (Tate Britain). © The Henry Moore Foundation. This plaster was the result of a commission from the Arts Council of Great Britain for the Festival of Britain. A single bronze was cast from it. speakers: Dr. Beth Harris and Dr. Steven Zucker. Created by Beth Harris and Steven Zucker.

Stéphane Couturier examines the transformation of desert into suburb. Stéphane Couturier, Fenetre, Eastlake Greens, San Diego, edition 4/8, 2001, dye coupler print, 130.81 x 107.95 x 2.54 cm (LACMA, © Stéphane Couturier) With Elizabeth Gerber, Museum Educator, Los Angeles County Museum of Art and Steven Zucker This Seeing America video was made possible thanks to major grants from the Terra Foundation and the Alice L. Walton Foundation. Find learning related resources here: https://smarthistory.org/seeing-america-2/

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.