PBS
Pbs Learning Media: Farming the Desert: The Science Behind Desertification
This lesson introduces students to the factors that contribute to desertification and solutions that have been implemented in the Sahel region of West Africa. A 21-page teaching guide is also provided. [4:39]
NASA
Nasa: Kepler's Second Law
This site from NASA states Kepler's second law of planetary motion and depicts its meaning with an informative diagram. Relates the law to conservation of energy principles and discusses the eccentricity of a satellite's (or a planet's)...