Four major parts of Earth work together as a complex system: rocks, water, air, and life. On a global scale, each part can be thought of as a sphere, roughly the same size and shape as the planet. The four parts are called the geosphere, hydrosphere, atmosphere, and biosphere.This lesson introduces students to the 4 spheres, including definitions, examples, and a practice in which students identify and describe the 4 spheres in photographs. Includes student note-sheet, photographs, and supplemen