  Word Problems with Length

Contributor: Rachel Lewis. Lesson ID: 12222

You have two feet, so they're easy to count. But what if you have to figure out how many feet make 36 inches or how many yards are in a mile? That'll happen some day, so learn the easy way to convert!

categories

Elementary

subject
Math
learning style
Kinesthetic, Visual
personality style
Lion, Beaver
Intermediate (3-5)
Lesson Type
Skill Sharpener

Lesson Plan - Get It!

Construction workers are building a new house right across the street from you. You overhear the foreman say that he needs the windows four times smaller than the front door. The front door is eight feet tall. How tall are the windows?

There are two main parts to a word problem.

• There is the information that we are given in the problem,
• and the question, or what we need to find out.

So, how are word problems with measurements different? In this lesson, you'll learn the four steps to solving a word problem using length measurements.

Look at the problem from the beginning of the lesson:

• The construction workers need windows 4 times smaller than the front door.
• The front door is 8 feet tall.
• How many feet is each window?

How can we solve this word problem with length measurements? We have a measurement in feet and we need to find a measurement with the same unit. We can solve this problem quite simply. Begin with what you know.

You know that you have a door that is 8 feet tall:

• 1 door = 8 feet

Next, you ask yourself, "What do we need to find out?" We need to find out the length of each window:

• 1 window = x feet

Then, you need to decide which operation to use. You know the windows are 4 times smaller (the word "smaller" tells us that we need to use the opposite of multiplication) than the door. You need divide to find the answer:

• 8 ÷ 4 = 2

Each window is two feet tall!

In some word problems, you need to convert, or change, one unit of measurement to another. To convert units, you must know how the units are related. Read the conversion chart below to review the conversions between inches, feet, yards, and miles:

 Customary Units of Length 1 foot (ft) = 12 inches (in) 1 yard (yd) = 3 feet (ft) 1 yard (yd) = 36 inches (in) 1 mile (mi) = 1,760 yards (yd) 1 mile (mi) = 5,280 feet (ft)

There are four basic steps to solving word problems when you need to convert units:

1. Look at the Customary Units of Length chart. What units will you need to convert to solve the problem?
2. How will you convert the units?
• To convert a larger unit to a smaller unit, use multiplication.
• To convert a smaller unit to a larger unit, use division.
1. Convert the units.
2. Solve the problem.

Look at an example:

Sara has 5 feet of fabric. She used 56 inches of fabric to make curtains for the new windows. How many inches of fabric does Sara have left?

1. We need to convert feet into inches. One foot equals 12 inches.
2. A foot is a larger unit than an inch, so we will multiply.
3. Now we can convert the number of feet of fabric by 12 inches:
• 5 feet x 12 inches = 60 inches
4. There are 60 inches in the 5 feet of fabric. If Sara uses 56 inches for the curtains, we can subtract 56 inches from the 60 inches of fabric:
• 60 inches – 56 inches = 4 inches

Solution: There are four inches of fabric left.

In this section, you learned how to solve word problems using customary units of length. You also learned how to convert between measurement units before you solve a problem. The examples showed you how length measurements can be used to solve word problems when building and designing a new house.

• Can you think of another time that you could use this skill?
• Have you ever needed to solve a problem to find the length of an object?

Share your thoughts with a parent or teacher.

Then, go to the Got It? section, where you will try an online practice activity.

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