UNIT OVERVIEW

Earth is much more than just rocks and soil. It is a system where land, water, air, and life work together all the time. When scientists talk about a system, they mean parts that are connected and affect each other.

Think of your body as a system. Your heart pumps blood, your lungs breathe air, and your stomach digests food. These parts work together to keep you alive. Earth works the same way. Its different parts connect and depend on each other.

In this unit, you will learn:

• What the four spheres of Earth are
• How these spheres interact with each other
• What the lithosphere is and what it is made of
• The three types of rocks and how they change in the rock cycle

By the end of this unit, you will understand how Earth works as one big system.

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