Matter can be measured using standard units. Standard units of the **English System** are used by the United States. These include such units as: inches, feet, yards, ounces, pounds, quarts, and gallons. The system used by other countries is called the **Metric System**. This system is based on units of ten. It includes units such as: centimeters, meters, kilometers, liters and grams.

Matter can be described by measurements such as length, area, and volume.

- Length is the number of units that fit along the edge of an object.
- Area is a measurement that tells the number of units that fit inside a surface. To find the area of a rectangular object is to multiply the length by its width (
*L*W=A*). - Volume describes how much space an object takes up. To find the volume, multiply its length by its width and its height (
*L*W*H=V*).

Weight is the measure of the pull of gravity between an object and Earth. Gravity is the attracting force between objects. Mass is a measurement of how much stuff is in a piece of matter. An object’s weight varies from place to place, but the mass stays the same. A scale can be used to measure weight.

Density is the amount of matter in a given space, or how tightly packed matter is. Density is what makes an object sink or float in liquid. For example a marble will be denser than water and will sink. A cork is not as dense as water and will float (*mass/volume = density*).