Down
| 1. | A glass or plastic container which is normally used for storing liquid. |
| 3. | The amount of work a machine does compared to the amount of energy needed to run the machine. |
| 6. | This type of precipitation is caused by pollution and is harmful to plants, animals, bodies of water, and buildings. (2 words) |
| 8. | An efficient type of light bulb. |
| 9. | A living creature that can breathe and move about. |
| 10. | To remove dirt or stains from something. |
| 12. | Thermal energy that travels in waves and can pass through empty space as well as some objects. |
| 14. | A layer in the atmosphere which blocks many of the sun's ultraviolet rays from reaching the earth. (2 words) |
| 16. | A type of potential energy that can be burned to supply heat, such as wood. |
| 17. | Harmful substances that are released and make our planet dirty, noisy, or unhealthy. |
| 23. | The invisible mixture of gases we breathe. |
|
|
Across
| 2. | A type of fuel formed from the remains of plants or sea creatures millions of years ago. (2 words) |
| 4. | This is the third planet from the sun. |
| 5. | This occurs when running water, sea waves, wind, or glaciers pick up and carry away materials from the earth's surface. |
| 7. | We must breathe this gas in the air to survive. |
| 11. | A person who helps or offers to do something without getting paid. |
| 13. | 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. | Fossil fuels are ____ resources because they can only be used once. |
| 19. | A type of fuel used in cars with internal-combustion engines. This is made from petroleum. |
| 20. | This ecosystem is hot and humid all year round. Chameleons, toucans, and chimpanzees all live here. |
| 21. | The large body of saltwater that covers about 70% of the earth's surface. |
| 22. | We use this term to describe the disappearance of forests due to land development, cultivation, or lumbering. |
| 24. | A plant with leaves, roots, and a single, woody trunk. |
|
