This is the third planet from the sun.

2) ______________________________

The large body of saltwater that covers about 70% of the earth's surface.

3) ______________________________

The apparent rise in the earth's temperature that scientists believe is caused by an increase in the amount of carbon dioxide and other gases in the air.

4) ______________________________

A physical agency caused by the movement of electrons, protons, manifesting itself as attraction, replusion, magnetic, luminous, and heating effects.

5) ______________________________

An efficient type of light bulb.

6) ______________________________

The disappearance of forests due to land development, cultivation, or lumbering.

7) ______________________________

This ecosystem is hot and humid all year round. Chameleons, toucans, and chimpanzees all live here.

8) ______________________________

Power derived from the fall of water from a higher to a lower level, and extracted by means of waterwheels or hydraulic turbines

9) ______________________________

Any useless material that is thrown away.

10) ______________________________

A layer in the atmosphere which blocks many of the sun's ultraviolet rays from reaching the earth.

11) ______________________________

A person who helps or offers to do something without getting paid.

12) ______________________________

Potentially dangerous to human beings or the environment

13) ______________________________

A type of fuel formed from the remains of plants or sea creatures millions of years ago.

14) ______________________________

To throw garbage on the ground instead of in a garbage can.

15) ______________________________

Performing or functioning in the least wasteful manner possible.