## Objective

Describe and perform rotations between congruent figures.

## Common Core Standards

### Core Standards

The core standards covered in this lesson

8.G.A.1.A— Lines are taken to lines, and line segments to line segments of the same length.

### Geometry

8.G.A.1.A— Lines are taken to lines, and line segments to line segments of the same length.

8.G.A.1.B— Angles are taken to angles of the same measure.

### Geometry

8.G.A.1.B— Angles are taken to angles of the same measure.

8.G.A.1.C— Parallel lines are taken to parallel lines.

### Geometry

8.G.A.1.C— Parallel lines are taken to parallel lines.

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.

### Geometry

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.

### Foundational Standards

The foundational standards covered in this lesson

4.MD.C.6

### Measurement and Data

4.MD.C.6— Measure angles in whole-number degrees using a protractor. Sketch angles of specified measure.

## Criteria for Success

The essential concepts students need to demonstrate or understand to achieve the lesson objective

- Describe
**rotations**with a direction, an angle of rotation, and a point to rotate around. - Use patty (transparency) paper to rotate images.
- Understand that in a rotation, every point on an original figure moves the same number of degrees and in the same direction around the same point to create the new figure.
- Understand that rotations preserve shape, size, orientation, area, perimeter, and parallel line relationships, but they do not preserve location.

## Tips for Teachers

Suggestions for teachers to help them teach this lesson

- This lesson focuses on rotations in isolation—how to do them and how to talk about them. Upcoming lessons will begin to combine rotations with the other rigid transformations.
- Similar to the video from Lesson 4, this video,Rotation, by PBS Learning Media introduces the concept of rotation and includes animation that can be helpful for students to visualize the movements, especially the importance of the point of rotation.

### Lesson Materials

*Optional*: Patty paper (transparency paper)*Optional*: 180° Protractor

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## Anchor Problems

Problems designed to teach key points of the lesson and guiding questions to help draw out student understanding

25-30 minutes

### Problem 1

Triangle $${{LMN}}$$underwent a single transformation to become triangle $${{PQR}}$$, shown below.

a.What single transformation maps triangle $${{LMN}}$$to triangle $${{PQR}}$$? Describe in detail.

b.Name two things that are the same about both triangles.

c.Name two things that are different about the triangles.

#### Guiding Questions

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### Problem 2

Perform the following rotations on figure $${{ABCD}}$$ below.

a.Rotate figure $${{ABCD}}$$$${90^{\circ}}$$ counter-clockwise around point $$A$$to create $$A'B'C'D'$$.

b.Rotate figure $${{ABCD}}$$ $${180^{\circ}}$$counter-clockwise around point $$A$$to create $$A''B''C''D''$$.

#### Guiding Questions

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## Problem Set

A set of suggested resources or problem types that teachers can turn into a problem set

15-20 minutes

Fishtank Plus Content

Give your students more opportunities to practice the skills in this lesson with a downloadable problem set aligned to the daily objective.

## Target Task

A task that represents the peak thinking of the lesson - mastery will indicate whether or not objective was achieved

5-10 minutes

Triangle $${QRS}$$was transformed to create triangle $${Q'R'S'}$$in the coordinate plane below.

a.Describe the transformation that maps $${QRS}$$ to $${Q'R'S'}$$.

b.Rotate figure $${Q'R'S'}$$ $${90^{\circ}}$$clockwise around the origin and draw the new figure $${{Q''R''S''}}$$. Describe a single transformation that maps triangle $${QRS}$$ to $${{Q''R''S''}}$$.

#### Student Response

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## Additional Practice

The following resources include problems and activities aligned to the objective of the lesson that can be used for additional practice or to create your own problem set.

- Examples where students identify and describe a rotation between two figures (limit to around the origin and around a point on the figure only), similar to Anchor Problem #1
- Examples where students perform rotations around either the origin or a point on the figure, similar to Anchor Problem #2
- Examples where students identify new coordinate points of a figure after it is rotated
- Error analysis of figures that appear to be rotated but the orientation is shifted

- EngageNY Mathematics Grade 8 Mathematics > Module 2 > Topic B > Lesson 10—Teacher Version: Classwork Exercises #1-5, Problem Set #3, skip #1-2
- Kuta Software Free Geometry Worksheets
*Transformations - Rotations*—strongly suggest having students use patty paper to experiment with and verify rotations

Lesson 5

Lesson 7