Lesson 1: Moving in the Plane
About this lesson
The purpose of this lesson is to introduce students to translations and rotations of plane figures and to have them describe these movements in everyday language. Expect students to use words like “slide” and “turn.” In the next lesson, they will be introduced to the mathematical terms. The term “transformation” is not yet used and will be introduced later in a later lesson.
In all of the lessons in this unit, students should have access to their geometry toolkits, which should contain tracing paper, graph paper, colored pencils, scissors, ruler, protractor, and an index card. For this unit, access to tracing paper and a straight edge are particularly important. Students may not need all (or even any) of these tools to solve a particular problem. However, to make strategic choices about when to use which tools (MP5), students need to have opportunities to make those choices. Apps and simulations should supplement rather than replace physical tools.
Lesson overview
 1.1 Warmup: Which One Doesn’t Belong: Diagrams (10 minutes)

1.2 Activity: Triangle Square Dance (25 minutes)
 Includes "Are you Ready for More?" extension problem
 There is a digital applet in this activity.
 Lesson Synthesis
 1.3 Cooldown: Frame to Frame (5 minutes)
Learning goals:
 Describe (orally and in writing) a translation or rotation of a shape using informal language, e.g., “slide,” “turn left,” etc.
 Identify angles and rays that do not belong in a group and justify (orally) why the object does not belong.
Learning goals (student facing):
 Let’s describe ways figures can move in the plane.
Learning targets (student facing):
 I can describe how a figure moves and turns to get from one position to another.
Required materials:
 copies of blackline master
 geometry toolkits
Required preparation:
 You will need the Triangle Square Dance blackline master for this lesson.
 Make 1 copy of all 3 pages for every 2 students.
 Assemble geometry toolkits.
 It would be best if students had access to these toolkits at all times throughout the unit.
 Toolkits include tracing paper, graph paper, colored pencils, scissors, ruler, protractor, and an index card to use as a straightedge or to mark right angles.
 Access to tracing paper is particularly important in this unit.
 Tracing paper cut to a smallish size (roughly 5" by 5") is best—commercially available “patty paper” is ideal for this.
 If using larger sheets of tracing paper, such as 8.5" by 11", cut each sheet into fourths.
Glossary:
 vertex  A vertex is a point where two or more edges meet. When we have more than one vertex, we call them vertices. The vertices in this polygon are labeled \(A\), \(B\), \(C\), \(D\), and \(E\).
 Access the complete Grade 8 glossary.
Standards
 This lesson builds on the standard:CCSS.4.MD.C.5MS.4.MD.5MO.4.GM.B.4
 This lesson builds towards the standard:CCSS.8.G.A.1MS.8.G.1MO.8.GM.A.1a
IM 6–8 Math was originally developed by Open Up Resources and authored by Illustrative Mathematics, and is copyright 20172019 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/mathcurriculum/.
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.
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