Lesson plan

# Lesson 3: Making Scaled Copies

teaches Alabama State Standards 7-17.
teaches Arizona State Standards 7.G.A.1
teaches Common Core State Standards MP3 http://corestandards.org/Math/Practice/MP3
teaches Common Core State Standards MP7 http://corestandards.org/Math/Practice/MP7
teaches Common Core State Standards MP5 http://corestandards.org/Math/Practice/MP5
teaches Common Core State Standards 7.G.A.1 http://corestandards.org/Math/Content/7/G/A/1
teaches Georgia State Standards MGSE7.G.1.
teaches Kansas State Standards 7.G.1.
teaches Minnesota State Standards 7.3.2.3.
teaches Minnesota State Standards 7.3.2.2.
teaches Minnesota State Standards 7.3.2.1.
teaches New York State Standards NY-7.G.1.
teaches Ohio State Standards 7.G.1.b.
teaches Ohio State Standards 7.G.1.a.
teaches Ohio State Standards 7.G.1.
teaches Pennsylvania State Standards CC.2.3.7.A.2.

# Lesson 3: Making Scaled Copies

In the previous lesson, students learned that we can use scale factors to describe the relationship between corresponding lengths in scaled figures. Here they apply this idea to draw scaled copies of simple shapes on and off a grid. They also strengthen their understanding that the relationship between scaled copies is multiplicative, not additive. Students make careful arguments about the scaling process (MP3), have opportunities to use tools like tracing paper or index cards strategically (MP5).

As students draw scaled copies and analyze scaled relationships more closely, encourage them to continue using the terms scale factor and corresponding in their reasoning.

Lesson overview

• 3.1 Warm-up: More or Less? (5 minutes)
• 3.2 Optional Activity: Drawing Scaled Copies (10 minutes)
• There is a digital applet in this activity.
• 3.3 Activity: Which Operations? (Part 1) (10 minutes)
• 3.4 Activity: Which Operations? (Part 2) (10 minutes)
• Includes "Are you Ready for More?" extension problem
• Lesson Synthesis
• 3.5 Cool-down: More Scaled Copies (5 minutes)

Learning goals:

• Critique (orally and in writing) different strategies (expressed in words and through other representations) for creating scaled copies of a figure.
• Draw a scaled copy of a given figure using a given scale factor.
• Generalize (orally and in writing) that the relationship between the side lengths of a figure and its scaled copy is multiplicative, not additive.

Learning goals (student facing):

• Let’s draw scaled copies.

Learning targets (student facing):

• I can draw a scaled copy of a figure using a given scale factor.
• I know what operation to use on the side lengths of a figure to produce a scaled copy.

Required materials:

• geometry toolkits

Required preparation:

• Make sure students have access to their geometry toolkits, especially tracing paper and index cards.

Glossary:

• Access the complete Grade 7 glossary.

Standards

• This lesson builds on the standard: CCSS.6.NS.B.3MS.6.NS.3MO.6.NS.B.3
• This lesson builds towards the standard: CCSS.7.RP.A.2MO.7.RP.A.2aMS.7.RP.2

IM 6–8 Math was originally developed by Open Up Resources and authored by Illustrative Mathematics, and is copyright 2017-2019 by Open Up Resources. It is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0). OUR's 6–8 Math Curriculum is available at https://openupresources.org/math-curriculum/.