An exoskeleton (external skeleton) is common in arthropods like insects, spiders, and crustaceans.

More familiar in the United States is the Fahrenheit scale in which the freezing point of water is 32°F (0°C) and the boiling point is 212°F (100°C). To convert from C° to F° use the formula:

\(F° = {9 \over 5}C° + 32\)

and to convert from F° to C° use:

\(C° = {5 \over 9} (F° - 32)\)

Force is applied to change an object's speed or direction of motion.

A proton is a subatomic particle found in the nucleus of an atom. It carries a positive electric charge.

An element in a solid state has atoms or molecules that are constricted and do not move freely. Solids maintain a constant volume and shape and exist at a lower temperature than liquids or gases.