This 6-minute clarifies the first living things to colonize land. [Cosmology and Astronomy playlist: Lesson 42 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 11-minute video lesson introduces the Big Bang theory of the origin of the universe. [Cosmology and Astronomy playlist: Lesson 7 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 8-minute video lesson looks at the birth of stars. [Cosmology and Astronomy playlist: Lesson 16 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 10-minute video lesson discusses black holes. [Cosmology and Astronomy playlist: Lesson 30 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 9-minute video lesson looks at Cepheid Variables. [Cosmology and Astronomy playlist: Lesson 31 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

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]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

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]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

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]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

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]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

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]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 12-minute video lesson discusses cosmic background radiation. [Cosmology and Astronomy playlist: Lesson 11 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 10-minute video lesson continues the discussion of cosmic background radiation. It looks at the redshift of the cosmic background Radiation. [Cosmology and Astronomy playlist: Lesson 12 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 7-minute video lesson considers the scale of cosmologial time. [Cosmology and Astronomy playlist: Lesson 13 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 6-minute video lesson contiues to look at the scale of cosmological time. [Cosmology and Astronomy playlist: Lesson 14 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 13-minute video lesson presents a framework for thinking about how many detectable civilizations are out there. [Cosmology and Astronomy playlist: Lesson 59 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 9-minute video lesson considers why we even care about the Drake Equation. It ponders the fraction of a planet's life when a civilization might be detectable. [Cosmology and Astronomy playlist: Lesson 60 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 7-minute video lesson reconciles the traditional Drake Equation. [Cosmology and Astronomy playlist: Lesson 61 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 6-minute video lesson takes a shot at estimating the number of detectable civilizations in the Milky Way Galaxy. [Cosmology and Astronomy playlist: Lesson 62 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 5-minute video lesson looks at more reasons why we haven't detected anything yet. [Cosmology and Astronomy playlist: Lesson 63 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This 13-minute video looks at the development of agriculture and writing in the Paleolithic and Neolithic eras of the Stone Age. [Cosmology and Astronomy playlist: Lesson 67 of 85]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.