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.

This 14-minute video lesson considers energy consumption required for tilling land. [Cosmology and Astronomy playlist: Lesson 84 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 Firestick Farming and how the indigenous Australians used fire to change their environment. [Cosmology and Astronomy playlist: Lesson 76 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 looks at the four fundamental forces: Gravity, weak interaction, electromagnetic force, and strong interaction. [Cosmology and Astronomy playlist: Lesson 15 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 looks at the predicted collision of the Milky Way Galaxy with Andromeda (forming "Milkomeda"). [Cosmology and Astronomy playlist: Lesson 37 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 how the Hawaiian Islands were formed by a stationary hot spot under the Pacific plate. [Cosmology and Astronomy playlist: Lesson 49 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 explains how we know about the Earth's core. It shows how S-wave shadow and P-wave detection patterns give us information about the core. [Cosmology and Astronomy playlist: Lesson 55 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 looks at Hubble Telescope images of galaxies. [Cosmology and Astronomy playlist: Lesson 6 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 looks at Hubble's Law. [Cosmology and Astronomy playlist: Lesson 26 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.