1. Estimate each product. Use a bar diagram if needed. 1. 2. 5.
6. A caterer is preparing meals for a party of 78 guests. If about of the guests want steaks, about how many steaks should the caterer bring?
Course 1, Lesson 4-2

2. ANSWERS 1. Sample answer: 2. Sample answer: 3. Sample answer:
6. 20 steaks
Course 1, Lesson 4-2

3. multiply and divide fractions?
The Number System
WHAT does it mean to
multiply and divide fractions?
Course 1, Lesson 4-2

4. Mathematical Practices
The Number System
Preparation for 6.NS.1 Interpret and compute quotients of fractions, and solve word problems involving division of fractions by fractions, e.g., by using visual fraction models and equations to represent the problem.
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.
7 Look for and make use of structure.
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. And a whole number using area models Using an equation
The Number System
To multiply a fraction
And a whole number using area models
Using an equation
Course 1, Lesson 4-2

6. The Number System
Commutative Property
Course 1, Lesson 4-2

7. Multiply a Whole Number by a Fraction
The Number System
Multiply a Whole Number by a Fraction
Words
Example
Write the whole number as a fraction. Multiply the numerators and multiply the denominators.
Write 5 as .
Multiply.
Simplify.
Course 1, Lesson 4-2

8. Shade of each of the first two columns.
Step-by-Step Example 1.
Find 2 × .
Use an area model. 1
Shade of each of the first two columns. 2
A total of has been shaded.
Shade on the third column.
Use an equation. 3
Estimate
2 × = 1
Using either method, 2 × is . 4
2 × = 5
Check for Reasonableness
2 × = ×
Write 2 as . 6
≈ 1
2 × 2
1 × 5 =
Multiply. =
Simplify.
Need Another Example?

9. Need Another Example?
Find 3 × .
Answer

10. Shade of each of the 4 columns.
Step-by-Step Example 2.
Use an area model. 1
Shade of each of the 4 columns. 2
A total of or 2 has been shaded.
Use an equation.
Estimate
× 4 = 2 3
× 4 =
× 4 = ×
Write 4 as .
3 × 4
5 × 1 =
Multiply. =
Simplify. Compare to the estimate.
= 2
Using either method, × 4 is 2 . 4
Need Another Example?

11. Need Another Example?
Find × 7.
or 4
Answer

12. Check for Reasonableness 1 ≈ 1
Step-by-Step Example 3.
Estimate
× 4 = 1 1
× 5 = ×
Write 5 as . 2
1 × 5
4 × 1 =
Multiply. 3
= or 1
Simplify. 4
Check for Reasonableness
1 ≈ 1 5
Need Another Example?

13. Need Another Example?
Find × 9.
or 1
Answer

14. A sloth spends of its life asleep. If a sloth lives to be
Step-by-Step Example 4.
A sloth spends of its life asleep. If a sloth lives to be
28 years old, how many years does it spend asleep?
Find of 28.
Estimate
of 30 is 24. 1 2
× 28 = ×
Write 28 as =
Multiply. 3
= or 22
Simplify. Compare to the estimate. 4 5
A sloth spends years of its life asleep.
Need Another Example?

15. Need Another Example?
A little brown bat spends of its life asleep. If a little brown bat lives to be 24 years old, how many years does it spend asleep?
20 years
Answer

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?
Course 1, Lesson 4-2

17. 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 answers:
To find the portion of a set
To find the amount of one set given its portion of another set
Course 1, Lesson 4-2

18. The Number System
Ratios and Proportional Relationships
The next lesson focuses on using diagrams to solve real-world problems involving the multiplication of fractions and whole numbers. Explain how today’s lesson helps prepare you for the next lesson.
Course 1, Lesson 4-2