1. Multiply. Write in simplest form. 1. 2. 3. 4.
5. To make a certain type of dress, it takes yards of material. How many yards of material would it take to make a dozen of those dresses?
Course 1, Lesson 4-5

2. ANSWERS 5.
Course 1, Lesson 4-5

3. multiply and divide fractions?
The Number System
WHAT does it mean to
multiply and divide fractions?
Course 1, Lesson 4-5

4. Mathematical Practices
The Number System
6.RP.3 Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations.
6.RP.3d Use ratio reasoning to convert measurement units; manipulate and transform units appropriately when multiplying or dividing quantities.
Mathematical Practices
1 Make sense of problems and persevere in solving them.
3 Construct viable arguments and critique the reasoning of others.
4 Model with mathematics.
6 Attend to precision.
Course 1, Lesson Common Core State Standards © Copyright National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.

5. Larger units to smaller units Smaller units to larger units
The Number System
To convert:
Larger units to smaller units
Smaller units to larger units
Course 1, Lesson 4-5

6. unit ratio dimensional analysis
The Number System
unit ratio
dimensional analysis
Course 1, Lesson 4-5

7. Since 1 foot = 12 inches, the unit ratio is .
Step-by-Step Example 1.
Convert 20 feet to inches.
Since 1 foot = 12 inches, the unit ratio is 1 2
Multiply by
Divide out common units, leaving
the desired unit, inches. 3
= 20 × 12 in.
Multiply. 4
= 240 in. 5
So, 20 feet = 240 inches. 6
Need Another Example?

8. Need Another Example?
Convert 2 miles to feet.
Answer
10,560 ft

9. Marco mixes cup of fertilizer with soil before
Step-by-Step Example 2.
Marco mixes cup of fertilizer with soil before
planting each bulb. How many fluid ounces of fertilizer does he use per bulb?
Since 1 cup = 8 fluid ounces, multiply by
Then, divide out common units. 1
= × 8 fl oz
Multiply. 2 3
= 2 fl oz 4
So, 2 fluid ounces of fertilizer are used per bulb.
Need Another Example?

10. Need Another Example?
At the grocery store, Miranda weighs 1.75 pounds of green beans for a recipe she wants to make. How many ounces of green beans did Miranda weigh?
28 oz
Answer

11. Convert 15 quarts to gallons.
Step-by-Step Example 3.
Convert 15 quarts to gallons.
Since 1 gallon = 4 quarts, and quarts are smaller units than
gallons, use the ratio 1 2
Multiply by
Divide out common units, leaving
the desired unit, gallons. 3
Multiplying 15 by is the same as
dividing 15 by 4. 4
= 3.75 gal 5
Need Another Example?

12. Need Another Example?
Convert 11 cups to pints.
Answer

13. So, Umeka needs 1 yards of fabric.
Step-by-Step Example 4.
Umeka needs 4 feet of fabric to make a costume for a play. How many yards of fabric does she need?
Since 1 yard = 3 feet, multiply by
Then, divide out common units. 1 3
Write 4 as an improper fraction.
Then divide out common factors. 2 1 3
Multiply. 4
So, Umeka needs 1 yards of fabric.
Need Another Example?

14. Need Another Example?
Tracy kicked a soccer ball 100 feet. How many yards did she kick the ball?
Answer

15. How did what you learned today help you answer the
The Number System
How did what you learned
today help you answer the
WHAT does it mean to
multiply and divide fractions?
Course 1, Lesson 4-5

16. How did what you learned today help you answer the
The Number System
How did what you learned
today help you answer the
WHAT does it mean to
multiply and divide fractions?
Sample answer:
To use fractions as ratios when converting measurement units
Course 1, Lesson 4-5

17. The Number System
Ratios and Proportional Relationships
Explain how your understanding of unit rates helped you to convert measurement units.
Course 1, Lesson 4-5