https://www.khanacademy.org/science/grade-7-science-tx/xe25057200abc6bd6:water-and-human-activities 2026-07-03T03:00:41.306580382Z Water and human activities Examine how human activities both benefit and harm freshwater systems, and learn how watersheds collect and move water across landscapes. Then, explore how people depend on ocean systems for resources, economic activities, and ecosystem services—and how those activities impact ocean health. unit