Lesson 17: Working with Rigid Transformations
About this lesson
In previous grades, students describe a sequence of rigid transformations that exhibits the congruence between two figures. To prepare students for future congruence proofs, this lesson asks students to come up with a systematic, pointbypoint sequence of transformations that will work to take any pair of congruent polygons onto one another. As the focus shifts to sequences of transformations between figures with more general characteristics rather than specific measurements, encourage students to explain how they know that their sequences will cause certain points or lines to coincide. When students consider how generalizable a strategy for defining sequences of rigid transformation is, they are looking for the structures of pairs of congruent figures (MP7).
This lesson was designed to be done without technology.
Lesson overview
 17.1 Warmup: Math Talk: From Here to There (5 minutes)

17.2 Activity: Card Sort: How Did This Get There? (20 minutes)
 Includes "Are you Ready for More?" extension problem

17.3 Activity: Reflecting on Reflection (10 minutes)
 Digital applet in this activity
 Lesson Synthesis
 17.4 Cooldown: Get This There (5 minutes)
Learning goals:
 Compare and contrast (orally) diagrams of transformations.
 Comprehend that the notation \(A'\) represents the image of point \(A\).
 Explain (orally and in writing) a sequence of transformations that take given points to another set of points.
Learning goals (student facing):
 Let’s compare transformed figures.
Learning targets (student facing):
 I can describe a transformation that takes given points to another set of points.
Required materials:
 Geometry toolkits
 Preprinted cards, cut from copies of the blackline master
Standards:
 This lesson builds on the standards:CCSS.8.G.A.2MS.8.G.2MO.8.GM.A.2aCCSS.HSGCO.A.4MS.GCO.4MO.G.CO.A.4
 This lesson builds towards the standards:CCSS.HSGCO.A.2MS.GCO.2MO.G.CO.A.2CCSS.HSGCO.A.5MS.GCO.5MO.G.CO.A.5
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