Introduction to Systems of Measurement

What you’ll learn to do: Make conversions between units in the U.S. and Metric systems of measurement

A highway sign showing the distance to several cities in kilometers.

Most countries use the metric system, while to United States uses their own way of measuring. In the U.S., distances are measured in miles, so when traveling to a foreign country, we cannot always understand the kilometer measurements. Because you are traveling from the U.S., you want to be able to convert kilometers to miles so you will be able to better navigate for yourself. This chapter will focus on unit conversions from the U.S. system to the metric system, as well as Fahrenheit to Celsius.

Before you get started in this module, try a few practice problems and review prior concepts.

readiness quiz


If you missed this problem, review this video.


If you missed this problem, review the following video.


If you missed this problem, review the video below.

In this section we will see how to convert among different types of units, such as feet to miles or kilograms to pounds. The basic idea in all of the unit conversions will be to use a form of [latex]1[/latex], the multiplicative identity, to change the units but not the value of a quantity.