ecology

3. - Harmful substances that make the air, water, or land dirty.
4. - A large body of salt water that covers most of the Earth's surface.
6. - Living creatures that can move and react to the world, like dogs, birds, and fish.
7. - The process of converting waste materials into new materials and objects.
12. - To use less of something, like energy or water, to help the environment.
14. - The natural world, including plants, animals, and landscapes.
16. - Everything around us, including the air, water, land, plants, and animals.
17. - To use something again instead of throwing it away.
18. - A large, flowing body of water that usually empties into a sea or ocean.

1. - Unwanted or unusable materials that are discarded.
2. - To keep safe from harm or destruction; to use less of something to preserve it.
3. - Living things that grow in the ground, like trees, flowers, and bushes.
5. - The clear liquid that falls as rain, fills rivers, lakes, and oceans, and is necessary for all life.
8. - Related to nature or environmentally friendly practices.
9. - Free from dirt, pollution, or waste.
10. - Tall plants with a trunk, branches, and leaves.
11. - A large area covered with trees and plants.
13. - To keep something safe from harm.
15. - The invisible gas that surrounds the Earth and which we breathe.
16. - The planet we live on.