Down
| 1. | The constant recycling and movement of water on Earth. Energy from the sun, plants, or animals causes water to evaporate. The water vapor rises in the atmosphere to form clouds. Rain returns the water from clouds back to the earth's surface. (2 words) |
| 2. | A person who helps or offers to do something without getting paid. |
| 3. | This occurs when running water, sea waves, wind, or glaciers pick up and carry away materials from the earth's surface. |
| 5. | An efficient type of light bulb. |
| 6. | We use this term to describe the disappearance of forests due to land development, cultivation, or lumbering. |
| 8. | This is another term for global warming. (2 words) |
| 11. | The invisible mixture of gases we breathe. |
| 13. | Harmful substances that are released and make our planet dirty, noisy, or unhealthy. |
| 14. | A glass or plastic container which is normally used for storing liquid. |
| 16. | This covers most of the earth's land, and is made up mostly of disintegrated rocks. |
| 19. | The ability to cause a change in matter. |
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Across
| 4. | A type of fuel formed from the remains of plants or sea creatures millions of years ago. (2 words) |
| 7. | To try to keep or maintain something in its original form. |
| 9. | We must breathe this gas in the air to survive. |
| 10. | Fossil fuels are ____ resources because they can only be used once. |
| 12. | A plant with leaves, roots, and a single, woody trunk. |
| 15. | A unit of electric power, equal to one joule of work per second. |
| 17. | A solid, hard black mineral that burns and gives off heat. It's formed from partly decayed vegetable matter that's under great pressure and heat in the earth. |
| 18. | To throw garbage on the ground instead of in a garbage can. |
| 20. | Fuels such as the wind and sun are ____ because they can generate power without being used up. |
| 21. | The amount of work a machine does compared to the amount of energy needed to run the machine. |
| 22. | The production of electric power from running water. |
| 23. | The protection and more efficient use of natural resources. |
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