Matt's parents want to have a deck added to the back of the house. Before contacting contractors, they want to get a general idea of how big of a deck they want. This way, when they talk to the contractors they will be able to get an estimate of how much it will cost. They need to know how long and how wide of a deck they want. What are the appropriate customary and metric units that Matt's parents should use to measure the width and length of the space where they want the new deck to be built?

In this concept, you will learn how to choose appropriate units for measuring lengths.

### Measurements

A **measurement** is the size or amount of something. Here, you will learn about measurements of length. There are two primary systems of measurement that you can use.

- The
**customary system**is the system of measurement primarily used in the United States. Units of length in this system include the inch, foot, yard, and mile. - The
**metric system**is the system of measurement primarily used in science and in countries outside of the United States. Units of length in this system include the millimeter, centimeter, and meter.

The different units of length are all related. The conversions below show how the units of length within each system are related.

**Relationships Between Common Customary Units of Length**

**Relationships Between Common Metric Units of Length**

\begin{align*} \begin{array}{rcl} 1\text{ millimeter }(mm) & = & \frac{1}{1000}\text{ meter }(m) = \frac{1}{10} \text{ centimeter }(cm)\\ 1\text{ centimeter} & = & \frac{1}{100}\text{ meter}\\ 1\text{ kilometer} & = & 1000\text{ meters} \end{array}\end{align*}

It's also good to know how the units of length are related between systems. Inches are similar in length to centimeters. Yards are similar in length to meters. Miles are similar in length to kilometers.

When you want to measure the length of something, the first thing you need to decide is what unit of measurement you want to use. You want to use the unit that most closely matches the object you are measuring. For example, you wouldn't want to measure the length of a city block in inches because the number would be too large and difficult to manage.

Here is an example.

Name the appropriate customary and metric units to use to measure the width of a sandbox.

First, imagine a sandbox. It is larger than a notebook, but not nearly as large as a city street. This means it would be best measured in feet, yards, or meters.

The answer is a sandbox would be best measured in feet, yards, or meters.

Here is another example.

Name the appropriate customary and metric units to use to measure the length of a book.

First, imagine a book. A book is a small item that you could hold in your hand. This means it would be best measured in inches or centimeters.

The answer is a book would be best measured in inches or centimeters.

Here is one more example.

Name the appropriate customary and metric units to use to measure the length of a street.

First, imagine a street. Streets are longer than football fields and something that you can drive on. This means it would be best measured in miles or kilometers.

The answer is a street would be best measured in miles or kilometers.

Once you have determined the appropriate unit of measurement, you can select an appropriate tool for measuring.

When measuring a small item, it is best to use a ruler. Many rulers have both customary units and metric units on them. You can use rulers to measure in millimeters, centimeters, and inches.

For larger items, you can use yard sticks, meter sticks, or measuring tape. For even longer distances where you are looking to measure in miles or kilometers, you could look on a map or use your car to determine the distance.

### Examples

#### Example 1

Earlier, you were given a problem about Matt and the new deck. His parents want to get an idea of how long and how wide they want their new deck to be so they can get an estimate for how much it will cost. Matt needs to know what units of measurement his parents should be using.

First, imagine a deck. It is larger than something you could hold in your hand, but it isn't as long as a road you would drive down. This means it would be best measured in feet, yards, or meters.

The answer is the deck would be best measured in feet, yards, or meters.

#### Example 2

Name the appropriate customary and metric units to use to measure the distance around a pool.

First, imagine a pool. It is larger than a notebook, but not as large as a football field. This means it would be best measured in feet, yards, or meters.

The answer is a pool would be best measured in feet, yards, or meters.

#### Example 3

Name the appropriate customary and metric units to use to measure the distance of a road race.

First, imagine a road race. A race that was only a few feet wouldn't be very fun! Races are typically measured in miles or kilometers.

The answer is a road race would be best measured in miles or kilometers.

#### Example 4

Name the appropriate customary and metric units to use to measure the length of a magazine.

First, imagine a magazine. A magazine is a small item like a book that you could hold in your hand. This means it would be best measured in inches or centimeters.

The answer is a magazine would be best measured in inches or centimeters.

#### Example 5

Name the appropriate customary and metric units to use to measure the width of a football field.

First, imagine a football field. A football field is larger than something you could hold in your hand, but isn't as long as a road you could drive down. This means it would be best measured in feet, yards, or meters.

The answer is a football field would be best measured in feet, yards, or meters.

### Review

Name the appropriate customary and metric units to use to measure each item.

- The height of a sunflower
- The depth to plant a seed in the soil
- The height of a tree
- The area of a garden plot
- The distance from a garden to the local farm store
- The length of a carrot
- A stretch of fencing
- The binding on a dictionary
- The distance between two seedlings planted in the ground
- The height of a corn stalk
- Your shoe size
- A piece of pipe for a water line
- The depth of a pond or lake
- The distance across a lake
- The distance from your home to school
- A bike trail from one end of a city to another end of the same city.

### Answers for Review Problems

To see the Review answers, open this PDF file and look for section 1.13.