Megan runs a small dairy farm with her family. Right now they have 85 cows and they milk each cow twice a day. They sell some of the milk in their own store at their farm, and the rest they turn into yogurt or cheese or sell to local grocery stores. Megan likes to keep track of how much milk she gets each day from her cows. What unit of measurement would be most appropriate for recording the amount of milk her cows are producing each day?

In this concept, you will learn how to choose appropriate tools and units for given customary measurement situations.

### Choosing Appropriate Tools for Customary Measurement

The **customary system of measurement** is the system of measurement primarily used in the United States. The customary system includes units of length, mass, and capacity.

When you want to measure something, the first thing you need to do is select an appropriate tool for measuring.

When measuring the length of an item or a distance, first consider how small or large it is. For a small item, it is best to use a **ruler**. A ruler is 1 foot (12 inches) in length and can be used to measure in inches. To measure items or distances that are slightly longer than a foot, you can use a **yardstick**. Yardsticks are 1 yard (3 feet) in length. To measure the length of an even longer item or distance, you can use a **measuring tape**. Measuring tapes can be uncurled to measure longer lengths. Measuring tapes usually show inches and feet.

When measuring the weight or mass of a small object, you can use a scale or a balance. You can use a scale to measure ounces and pounds.

When measuring units of capacity in cooking, you can use measuring cups and measuring spoons. Standard measuring cups come in 1 cup,

Here is an example.

Choose the appropriate tool for measuring the weight of an apple.

First, notice that you are looking for the weight of a small object. This means you should use a balance or a scale to do the measurement.

The answer is the weight of an apple could be measured with a scale.

Here is another example.

Choose the appropriate tool for measuring the length of a caterpillar.

First, notice that you are looking for the length of a small item. This means you should use a ruler to do the measurement.

The answer is the length of a caterpillar could be measured with a ruler.

When you need to measure something, always consider the most reasonable unit to use before measuring. If you choose a unit that is too small, you will get a large number that is hard to keep track of. If you choose a unit that is too large, it will be difficult to be precise in your measurement.

Let's look at an example.

Choose the appropriate customary unit to measure the weight of a jar of jam.

First, notice that you are looking for a weight. A jar of jam is relatively small and likely weighs less than a pound. This means it would be best measured in ounces.

The answer is the weight of a jar of jam would be best measured in ounces.

### Examples

#### Example 1

Earlier, you were given a problem about Megan and her family's dairy farm.

Megan wants to keep track of the amount of milk her 85 cows are producing each day and needs to know what unit of measurement would be most appropriate to use.

First, Megan should keep in mind that she is looking for a capacity. The amount of milk that 85 cows produce each day is a large amount. This means it would be best measured in gallons.

The answer is Megan should record the amount of milk produced by her cows each day in gallons.

#### Example 2

What tool and unit would you use to measure the height of a tree?

First, notice that you are looking for a height. A typical tree is more than a few feet tall. This means you should use a measuring tape to do the measurement.

Next, think about the unit. A tree is more than a few feet tall, but much less than a mile tall. It would make sense to measure the height of a tree in feet or yards.

The answer is the height of a could be measured with a measuring tape in feet or yards.

#### Example 3

What is the best tool to measure milk needed for a recipe?

First, notice that you are looking for a volume or capacity for cooking. This means you should use a measuring cup to do the measurement.

The answer is the volume of milk needed for a recipe could be measured with a measuring cup.

#### Example 4

What is the best tool to measure the dimensions of a garden plot?

First, notice that you are looking for lengths. A typical garden plot is more than a few feet long. This means you should use a measuring tape to do the measurement.

The answer is the dimensions of a garden plot could be measured with a measuring tape.

#### Example 5

What is the best tool to measure the weight of a bunch of bananas?

First, notice that you are looking for a weight. A typical bunch of bananas is something that you can carry, so it is not too big. This means you should use a balance or a scale to do the measurement.

The answer is the weight of a bunch of bananas could be measured with a scale.

### Review

Choose the appropriate tool for the following measurements.

- The weight of a violin
- The volume of a small amount of oregano
- The volume of a glass of milk
- The length of one side of your desk
- Sugar for a cup of coffee
- The amount of sugar needed for a cake
- The weight of a person

Choose the appropriate unit for the following measurements.

- The length of a football field
- The volume of a car’s gas tank
- The length of an insect
- The weight of a tennis shoe
- The distance a person runs in 1 hour
- The amount of water in a large drum
- The amount of water in a pool
- The size of a child’s foot

### Review (Answers)

To see the Review answers, open this PDF file and look for section 3.20.