UNIT OVERVIEW

Every day you breathe air, feel the warmth of the Sun, and see the sky above you. But have you ever wondered what that air is made of, or why the Sun shines?

In this unit, you will learn about two big topics:

1. The atmosphere – the blanket of air around Earth that protects us and keeps us alive.
2. Stars – giant balls of hot gas in space, including our Sun, which are born, live, and eventually die.

By the end of this unit, you will be able to:

• Name and describe the layers of the atmosphere
• Explain the greenhouse effect and why global warming is a problem
• Describe how stars are born, how they live, and how they die

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