Identify Earth's four spheres, the geosphere, hydrosphere, atmosphere, and biosphere, and describe how they interact.
Scientists organize Earth into four big systems, called spheres, to make sense of how the planet works. The geosphere is all the solid and molten rock: mountains, soil, the crust, and Earth's deep interior. The hydrosphere is all of Earth's water: oceans, lakes, rivers, ice, and water vapor. The atmosphere is the layer of gases surrounding the planet. The biosphere is every living thing, from bacteria to whales to you.
These four spheres are not separate; they constantly interact. Rain, from the hydrosphere, falls on a mountain, the geosphere, and helps a forest, the biosphere, grow, while the trees release gases into the air, the atmosphere. Almost every Earth event you can think of involves more than one sphere working together.
Mastery looks like: They can name and define all four spheres and identify which spheres are involved in a real Earth event or interaction.
Common stumbles: Confusing hydrosphere and atmosphere, since water vapor can seem to belong to both; forgetting living things are their own sphere, the biosphere, rather than part of the geosphere.