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SESSION 3

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Ideas About Multiplication as Scaling

Learning Targets

Understand multiplication as scaling.
Use patterns to understand how the size of a product compares to the size of its factors.

LESSON 21 • Understand Multiplication as Scaling

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Start

Which Would You Rather?

A

2 pears

B

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CONNECT TO CULTURE Optional

Dubai is a city in the United Arab Emirates (UAE), in the Middle East. It is a cultural and financial center, as well as a popular tourist destination.

What skyscrapers have you seen?

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The following expressions represent the heights, in feet, of three skyscrapers in Dubai. Use reasoning to order the skyscrapers from least to greatest height. Do not find any of the products. Explain your reasoning.

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Almas Tower

1,287

Princess Tower

1,287

23 Marina Tower

1,287

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CONNECT TO CULTURE Optional

Two of the five entrances to Yellowstone National Park are in West Yellowstone, Montana and Cody, Wyoming. In 1872, Yellowstone became the world’s first national park.

What national parks have you visited?

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Connect to Culture (Teacher’s Guide page 424a)

Engage students in sharing what they know about the context before you add the information given here.

Two of the five entrances to Yellowstone National Park are in West Yellowstone, Montana and Cody, Wyoming. In 1872, Yellowstone became the world’s first national park. It covers an area of 28,000 square miles and is home to a large variety of wildlife including elk, bison, grizzly bears, black bears, wolves, and many smaller species. Many communities of Native Americans have maintained relationships with the land, which includes geological features, such as geysers, steam vents, naturally colorful hot springs, fossilized forests, and obsidian (volcanic glass). Ask students if they have visited any national parks in the U.S. or in other countries around the world.

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In 2010, the population of Cody, Wyoming was 9,520 people. That year, the population of �West Yellowstone, Montana was about

9,520 people. To compare the populations

of the two towns, Metin says the population of

Cody was about of the population of West

Yellowstone. Is he correct? Explain your answer.

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Magdelena says that the product of a given number and a fraction is always less than the given number. Is Magdelena correct? Explain and give an example.

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You can compare the size of a product to the size of the factors in a multiplication equation if you know whether the factors are greater than, less than, or equal to 1.

Part A Write a multiplication equation (different than any in this lesson) in which the product is greater than both of its factors. At least one factor should be a fraction. Draw a model to support your answer.

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Solution

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You can compare the size of a product to the size of the factors in a multiplication equation if you know whether the factors are greater than, less than, or equal to 1.

Part B Write a multiplication equation (different from any in this lesson) in which both factors are fractions and the product is less than both of its factors. Draw a model to support your answer.

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Solution

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Close: Exit Ticket

How does compare to ? Explain your

reasoning.

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