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Contributor: Meghan Vestal. Lesson ID: 11305
Is your foot a foot long? How long is your thumb? How would you measure your yard? Listen to a measurement song and get some online practice as you learn about the measurement system used in the U.S.!
What do these tools have in common?
Throughout the world, there are primarily two types of measurement systems that are used: customary units and metric units.
In the United States, customary units, such as inches, feet, pounds, and gallons, are used. The rest of the world relies on the metric system of measurement. Metric units include centimeters, kilometers, grams, and liters.
In this series, you will learn about the customary system of measurement used in the United States.
Look at the question at the beginning of the lesson.
In this lesson, you will be learning about customary units of length.
A ruler and a tape measurer are both used to measure length. You will learn about the different tools used to measure length later in the lesson.
For now, let's define length and find out what are customary units of length.
Length describes the distance from one point to another point. Length can be as short as the distance from your eye to your nose, or it can be as long as the distance from the United States to China.
Since distances of length can vary so much, scientists and mathematicians created different units of length that are used depending on how much length needs to be measured.
The different customary units of length are inches, feet, yards, and miles. Think about all the ways you have used or have heard these terms used.
Make a thumbsup sign with your hand. Then, move the tip of your thumb down. The distance from your knuckle to the tip of your thumb is about one inch.
Inches are used to measure small objects, such as books, pencils, or a placemat.
The next customary unit used to measure length is a foot. There are 12 inches in a foot. The distance from your elbow to your hand is about one foot.
Feet are used to measure small and mediumsized objects, such as people, the size of a room, or the length of a couch.
Another unit used to measure length is a yard. There are three feet in a yard.
There are 36 inches in a yard. Yards are used to measure large distances, such as a football field or garden.
Finally, miles are also used to measure length. There are 5,280 feet in a mile.
Miles are used to measure very large distances. Typically, when miles are being used, you are unable to see the other point you are measuring to from the starting point.
Examples of when to use miles include figuring out the distance from your house to the market, or the distance from California to Florida.
Let's get ready to look at some more examples of when to use each unit of length.
Copy the following chart onto a separate piece of paper:
Inch 
Foot 
Yard 
Mile 

Watch the review video below to practice with several examples about when to use inches, feet, yards, and miles. As you watch, write the examples you hear in the correct column on your chart.
Inches, Feet, and Yards Video from Cassie Lindsey:
Add those to your chart.
Finally, make a list of all the tools you can think of that are used to measure length. Remember to include the two examples from the beginning of the lesson on your list.
There are three main tools used for measuring length: rulers, yardsticks, and tape measurers.
You now know the different customary units used for measuring length and the tools used for measuring length.
Move on to the Got It? section to learn more about when to use each unit and how to use these tools to measure length.