This document provides a lesson on multiplying fractions and decimals. It includes: - An exploratory challenge for students to calculate products of decimals and prove the correct placement of the decimal point. - Examples of multiplying decimals, with the rule that the number of decimal places in the product equals the sum of decimal places in the factors. - Additional word problems applying decimal multiplication, with worked out solutions. - A closing discussion of using factor information to determine the maximum place value and number of decimal digits in a product.

1. Module 2 Lesson 11 Fraction Multiplication and the Products of Decimals.notebook
December 18, 2013
Lesson 10 Homework Review
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2. Module 2 Lesson 11 Fraction Multiplication and the Products of Decimals.notebook
December 18, 2013
MODULE 2 Arithmec Operaons Including
Division of Fracons
Topic B: Mul‐Digit Decimal Operaons—Adding,
Subtracng, and Mulplying
Lesson 11: Fracon Mulplicaon and the
Products of Decimals
Student Outcomes
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Students use esmaon and place value to determine the placement of the decimal point in products and to determine that the size of the product is relave to each factor.
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Students discover and use connecons between fracon mulplicaon and decimal mulplicaon.
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Students recognize that the sum of the number of decimal digits in the factors yields the decimal digits in the product.
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3. Module 2 Lesson 11 Fraction Multiplication and the Products of Decimals.notebook
December 18, 2013
Exploratory Challenge
You will not only solve each problem, but your groups will also need to prove
to the class that the decimal in the product is located in the correct place. As a
group, you will be expected to present your informal proof to the class.
1. Calculate the product.
Proofs that the decimal is in the right place...
(hint: try fracons or esmaon)
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4. Module 2 Lesson 11 Fraction Multiplication and the Products of Decimals.notebook
December 18, 2013
2. Xavier earns $11.50 per hour working at the nearby grocery store. Last week,
Xavier worked for 13.5 hours. How much money did Xavier earn last week?
Remember to round to the nearest penny.
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5. Module 2 Lesson 11 Fraction Multiplication and the Products of Decimals.notebook
December 18, 2013
34.62
x 12.8
443.136
11.5
x 13.5
155.25
Do you see a connecon between the number of decimal digits in the
factors and the product?
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ú In the first problem, there are two decimal digits in the first factor
and one decimal digit in the second factor, which is a total of three
decimal digits. The product has three decimal digits.
ú In the second problem, both factors have one decimal digit for a
total of two decimal digits in the factors. The product also has two
decimal digits.
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6. Module 2 Lesson 11 Fraction Multiplication and the Products of Decimals.notebook
December 18, 2013
1. Calculate the product
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7. Module 2 Lesson 11 Fraction Multiplication and the Products of Decimals.notebook
December 18, 2013
2. Kevin spends $11.25 on lunch every week during the school year. If there are
35.5 weeks during the school year, how much does Kevin spend on lunch over the
enre school year? Remember to round to the nearest penny.
Kevin would spend $399.38
on lunch over the enre
school year.
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8. Module 2 Lesson 11 Fraction Multiplication and the Products of Decimals.notebook
December 18, 2013
3. Gunnar’s car gets 22.4 miles per gallon, and his gas tank can hold 17.82
gallons of gas. How many miles can Gunnar travel if he uses all of the gas in the
gas tank?
Gunnar can drive 399.168
miles on an enre tank of
gas.
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9. Module 2 Lesson 11 Fraction Multiplication and the Products of Decimals.notebook
December 18, 2013
4. The principal of East High School wants to buy a new cover for the sand pit
used in the long jump compeon. He measured the sand pit and found that
the length is 29.2 feet and the width is 9.8 feet. What will the area of the new
cover be?
The cover should have
an area of
286.16 square feet.
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10. Module 2 Lesson 11 Fraction Multiplication and the Products of Decimals.notebook
December 18, 2013
Closing
§ How can we use informaon about the factors to determine the largest place
value of the product and the number of decimal digits in the product?
Please take out your exit ticket for Lesson 11, close your
binder, and complete the exit ticket. This will be collected.
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