How water cycles on Earth.

Watch the next lesson: https://www.khanacademy.org/science/biology/ecology/biogeochemical-cycles/v/carbon-cycle

Missed the previous lesson? Watch here: https://www.khanacademy.org/science/biology/ecology/biogeochemical-cycles/v/biogeochemical-cycles

Ecology on Khan Academy: Why are polar bears found only in the Arctic? Why does mildew grow in your shower and not (hopefully) in your sock drawer? Learn how ecologists study the interactions between organisms and their environment, and how these interactions affect where, and in what numbers, different types of organisms are found.

About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content.

For free. For everyone. Forever. #YouCanLearnAnything

Subscribe to KhanAcademy: https://www.youtube.com/subscription_center?add_user=khanacademy