This lesson shows how to write a fraction as a decimal number.
Understanding alternate coordinate systems. Created by Sal Khan.
This 9-minute video lesson considers various theories about the size of the universe. [Cosmology and Astronomy playlist: Lesson 19 of 85]
This 7-minute video lesson looks at apsidal precession (Perihelion Precession) and Milankovitch Cycles. [Cosmology and Astronomy playlist: Lesson 75 of 85]
This 7-minute video lesson addresses the question: Are southern hemisphere seasons more severe because of the eccentricity in Earth's orbit? [Cosmology and Astronomy playlist: Lesson 72 of 85]
This 11-minute video lesson looks at the process of a star becoming a red giant. [Cosmology and Astronomy playlist: Lesson 17 of 85]
This 10-minute video lesson looks at the beginnings of life on Earth. Life and photosynthesis start to thrive in the Archean Eon. [Cosmology and Astronomy playlist: Lesson 39 of 85]
This 10-minute video lesson contiues to discuss the beginnings of life on Earth. The ozone layer and eukaryotes show up in the proterozoic eon. It includes the great oxygenation event (oxygen catastrophe). [Cosmology and Astronomy playlist: Lesson 40 of 85]
This 10-minute video lesson continues to discuss the beginnings of life on Earth. It looks at the Cambrian explosion and biodiversity in the Phanerozoic Eon. [Cosmology and Astronomy playlist: Lesson 41 of 85]
This 6-minute clarifies the first living things to colonize land. [Cosmology and Astronomy playlist: Lesson 42 of 85]
This 11-minute video lesson introduces the Big Bang theory of the origin of the universe. [Cosmology and Astronomy playlist: Lesson 7 of 85]
This 8-minute video lesson looks at the birth of stars. [Cosmology and Astronomy playlist: Lesson 16 of 85]
This 10-minute video lesson discusses black holes. [Cosmology and Astronomy playlist: Lesson 30 of 85]
This 9-minute video lesson looks at Cepheid Variables. [Cosmology and Astronomy playlist: Lesson 31 of 85]
This 10-minute video lesson discusses chronometry and the relatively recent changes in our ability as a species to shine light on our deep past. [Cosmology and Astronomy playlist: Lesson 81 of 85]
This 13-minute video lesson discusses collective learning and how symbolic language drives collective learning and how this is one of the truly differentiating aspects of human beings relative to the rest of the animal kingdom. [Cosmology and Astronomy playlist: Lesson 82 of 85]
This 12-minute video lesson looks at the structure of the earth. The discussion includes the crust, mantle, core, lithosphere, asthenosphere, mesosphere, outer core, and inner core. [Cosmology and Astronomy playlist: Lesson 50 of 85]
This 4-minute video lesson provides a correction for the time difference calculation by taking into account that there is no year 0. [Cosmology and Astronomy playlist: Lesson 66 of 85]
This 2-minute video lesson provides a correction for the previous video on the radious of the observable universe. [Cosmology and Astronomy playlist: Lesson 9 of 85]
This 12-minute video lesson discusses cosmic background radiation. [Cosmology and Astronomy playlist: Lesson 11 of 85]