Unit 3: Transformations

Unit 3 Learning Targets 

LT 3-1: I can identify and perform a reflection on a geometric figure.

LT 3-2: I can identify and perform a translation on a geometric figure.

LT 3-3: I can identify and perform a reflection on a geometric figure.

LT 3-4: I can classify rigid transformation and write rules to describe them.

LT 3-5: I can identify types of symmetry.

LESSON 3-1

Reflections

Reflections are rigid motions across a line of reflection. Students will create an image given a preimage and the line of reflection both on a coordinate plane and without the use of a coordinate plane.

Help Videos:

●       What Is a Reflection?

●       What Properties of a Figure Stay the Same After a Reflection?

Practice:

3-1 Math XL

LESSON 3-2

Translations

A translation is a rigid motion that moves all points of the preimage the same distance in the same direction. A translation is the composition of two reflections.

Help Videos:

●       What Properties of a Figure Stay the Same After a Translation?

●       How Do You Use Coordinates to Translate a Figure Diagonally?

Practice:

3-2 Math XL

LESSON 3-3

Rotations

Rotation is a rigid motion described by its center of rotation and angle of rotation. Any rotation can be described by two reflections whose lines of reflection meet at the center of rotation at half the angle of rotation.

Help Videos:

●       What Properties of a Figure Stay the Same After a Rotation? 

Practice:

3-3 Math XL

LESSON 3-4

Classification of Rigid Motions

Any composition of rigid motions can be represented by a combination of at least two of the following: a translation, reflection, rotation, or glide reflection.

Help Videos:

●       How Do You Graph a Glide Reflection?

●       What Is a Congruence Transformation, or Isometry?

Practice:

3-4 Math XL

LESSON 3-5

Symmetry

A figure that can be mapped onto itself using rigid motions is symmetric. Rotational symmetry uses rotation to map a figure onto itself, and reflectional symmetry uses reflection to map a figure onto itself.

Help Videos:

●       What is Rotational Symmetry?

●       How Can You Tell If a Figure Has Line Symmetry?

Practice:

3-5 Math XL

Unit 3 Vocabulary

●       perpendicular bisector

●       rigid motion

●       composition of rigid motions 

●       glide reflection 

●       point symmetry

●       reflectional symmetry

●       rotational symmetry