The metric system is an internationally agreed decimal system of measurement. It is now often used as a synonym for "SI" or the "International System of Units" — the official system of measurement in almost every country in the world.
In this lesson, we will learn about metric units of measurement that are used for length, weight, time and capacity or volume. While U.S. customary measurement units include pounds, inches and gallons, Metric measurement units include kilograms, centimeters and liters.
In the United States, Customary units are more popular in usage than metric units. However, if you go to a store there, you might see both sets of measurements like '64 ounces/1.89 liters' written on products like juice bottles and cereal boxes.
Standard Units of Length
We will begin by discussing standard units of length. Metric units for length are used to measure lengths, heights and distances, like the distance between two cities. For example, the distance from Phoenix to Las Vegas is 460 kilometers. So, the standard unit of length in metric units is kilometers. On a smaller scale, such as measuring the length of a pencil, we use centimeters. In the metric system, other units for length are millimeters and meters.
Standard Units of Weight
Now, if we wanted to find how much a pet cat weighs, we would see its weight in kilograms. It might weigh something like 5 kilograms. If we weighed letters for mailing, we would use grams in the metric system.
Standard Units of Capacity
If we wanted to measure the capacity of gasoline, we would measure it in metric unit such as liter and if we wanted to measure the capacity of a swimming pool, we would use metric unit such as kiloliter.
Standard Units of Time
To tell time, we use seconds, minutes and hours to tell time. For example, we will say that we will come over at 6 p.m. for dinner.
