Unit 2
Similar Polygons
Dilations, Similarity, and Introducing Slope
Lesson 7
8.G.A.2: Understand that a two-dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections, and translations; given two congruent figures, describe a sequence that exhibits the congruence between them.
8.G.A.4: Understand that a two-dimensional figure is similar to another if the second can be obtained from the first by a sequence of rotations, reflections, translations, and dilations; given two similar two-dimensional figures, describe a sequence that exhibits the similarity between them.
Expressions and Equations
8
All, Some, None: Congruence and Similarity
Unit 2 ● Lesson 7
1 min individual - 1 min team share - 3 mins class share
Always True
Sometimes True
Page 196
Sometimes True
Never True
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
Let’s look at sides and angles of similar polygons.
Unit 2 ● Lesson 7
We will be able to know the relationship between angle measures and side lengths in similar polygons so that we can decide if two polygons are similar just by looking at their angle measures.
Learning
Goal
8
Where were we? Where are we? Where are we going?
Unit 2 ● Lesson 7
Agenda Review
You are successful today when...,
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
Unit 2 ● Lesson 7
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
7.1 Activity: Are They Similar?
I know the relationship between angle measures and side lengths in similar polygons
10 mins total
2 questions: 4 min individual - 2 mins group - 4 min class share
pg 197
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
7.1 Activity: Are They Similar?
I know the relationship between angle measures and side lengths in similar polygons
Clare is correct. The angle measures in similar polygons are the same so these polygons can not be similar. Priya is not right: the side lengths of these polygons are the same but that is not enough to conclude that they are similar.
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
7.1 Activity: Are They Similar?
I know the relationship between angle measures and side lengths in similar polygons
Both Jada and Lin are incorrect. Jada: The scale factor between the short sides of the rectangles and the scale factor between the long sides are not the same. Lin: The scale factor for dilating one set of sides can not be different than the scale factor for dilating the other set of sides.
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
7.2 Activity: Find Someone Similar
I know the relationship between angle measures and side lengths in similar polygons
15 mins total
5 min set up - 5 min to find your match - 5 mins class share
Your task is to find someone else in the class who has a similar
(not congruent) figure to yours.
pg 199
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
7.3 Activity: Find Someone Similar
I know the relationship between angle measures and side lengths in similar polygons
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
Dilations with no Grid
I know the relationship between angle measures and side lengths in similar polygons
8
Lesson Synthesis
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
Dilations with no Grid
I know the relationship between angle measures and side lengths in similar polygons
8
Lesson Synthesis
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
A Single Dilation of a Triangle
Unit 2 ● Lesson 7
8
Cool-down
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
Unit 2 ● Lesson 7
Learning
Targets
8
8
Glossary
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
Glossary
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
Glossary
Unit 2 ● Lesson 5
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
Glossary
8
Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Open Up Resources, with adaptations CC BY Illustrative Mathematics.
This slide deck is copyright 2020 by Kendall Hunt Publishing, https://im.kendallhunt.com/, and is licensed under the Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0), https://creativecommons.org/licenses/by-nc/4.0/.
All curriculum excerpts are under the following licenses:
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/.
Adaptations and updates to IM 6–8 Math are copyright 2019 by Illustrative Mathematics, and are licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).
Adaptations to add additional English language learner supports are copyright 2019 by Open Up Resources, and are licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).
The Illustrative Mathematics name and logo are not subject to the Creative Commons license and may not be used without the prior and express written consent of Illustrative Mathematics.
8