In this topic you will learn how matter can be measured in different ways.

Systems of standard units have been developed to measure matter. A standard unit is a unit of measure that people agree to use. Standard units of measure in the English system include pounds, yards, and gallons. This system is used most commonly in the United States.

Most countries and all scientists use standard units of the metric system. The metric system is a system of measurement based on units of 10. One meter is divided into 100 centimeters. A meter is a bit longer than a yard.

Standard units are used to measure things in several ways. Length is the number of units that fit along one edge of something. Length can be measured in centimeters, meters and other units.

Area is the number of unit squares that fit a surface. Area is measured in units such as square centimeters or square inches. An easy way to find the area of a rectangle is to multiply its length by its width.

Volume is the amount of space an object takes up. It measures the number of cubes that can fit in an object. To find the volume of a solid rectangle, multiply its length by its width by its height. You can also measure the volume of a liquid.

Matter can be measured by weight. Mass and weight may seem similar, but they are not the same. Weight is the pull of gravity between an object and Earth. Gravity is an attracting force between objects. Weight can be measured by using a scale.

Density is the amount of matter in a given space. It describes how tightly packed matter is. It is the mass in a given unit of volume. The density of an object is measured in grams per cubic centimeter. The air inside a hot-air balloon is less dense than the air outside the balloon. This is because the heat energy inside the balloon causes air particles to move about quickly and spread out. Outside the balloon, the air particles are cooler, so they don't move as much and are more dense.

We depend on standard units of measure every day. We have to agree on units of measure to make purchases and to make plans for many projects in our daily lives.