IM1 – G-CO-4 Lesson 2 Reflections
Moving an Object In 2 Dimensions
Mr. Deyo
G.CO.4 Develop definitions of rotations, reflections, and translations in terms of angles, circles,
perpendicular lines, parallel lines, and line segments.
Title: IM1 – G-CO-4 Lesson 2 Reflections
Date:
Learning Target
By the end of the period, I will create a
definition of reflection in 2 dimensions and
apply that definition to a given object.
I will demonstrate this by completing FourSquare Notes and by solving problems in a
pair/group activity.
Home Work 1-2-3:
2) Section ______
TxtBk. Problems_________
Solved and Put in Binder?
Date
1) Class 4-Square Notes Put In Binder?
3) Section ______
Notes Copied on blank sheet
of paper in Binder?
Table of Contents
Description
Date Due
Storm Check (Think, Write, Discuss, Report)
Questions on which to ponder and answer:
1. How are the two images similar?
2. How are they different?
3. How can these two images be related to math?
Reflection Vocabulary
1) Pre-Image
2) Image
3) Axis of Reflection
Sketch
Friendly Definition
DAY 2
1. Review word
Friendly Definition
Physical Representation
DAY 1
1. Use Visuals
2.
Introduce the word
Friendly Definition
Physical Representation
3.
Use Cognates
4.
Write friendly definition
5.
Physical Representation
2. Draw a sketch
Word List
Wordwork
1.
2.
3.
4.
Sentence
DAY 3 and/or DAY 4
1. Review the word
Friendly Definition
Physical Representation
DAY 5
1. Review the word
Friendly definition
Physical Representation
2. Show how the word works
Synonyms/antonym
Word Problems
Related words/phrases
Example/non-example
3. Write a sentence
at least 2 rich words (1 action)
correct spelling
correct punctuation
correct subject/predicate agreement
clear and clean writing
Notes:
REFLECTION (Flip):
takes an image and
makes a mirror image in a plane
across a given axis of reflection
Reflections PRESERVE:
Size
Shape
CHANGE:
Orientation (flipped)
Storm Check (Think, Write, Discuss, Report)
What is the difference between a translation
and a reflection?
A translation ____________________________
_______________________________________.
A reflection _____________________________
_______________________________________.
The BLUE pentagon is the PRE-IMAGE and the GREEN one is
the IMAGE. How would you describe the reflection?
The IMAGE has reflected across ____________.
A
E
E’
A’
ABCDE
D
D’
A’B’C’D’E’
Coordinates for Point A
B
(_____ , _____)
Coordinates for Point A’
C
C’
B’
(_____ , _____)
Coordinates for Point B
(_____ , _____)
Coordinates for Point B’
(_____ , _____)
The BLUE pentagon is the PRE-IMAGE and the GREEN one is
the IMAGE. How would you describe the reflection?
The IMAGE has reflected across ____________.
A
E
E’
A’
ABCDE
D
D’
A’B’C’D’E’
Coordinates for Point C
B
(_____ , _____)
Coordinates for Point C’
C
C’
B’
(_____ , _____)
Coordinates for Point D
(_____ , _____)
Coordinates for Point D’
(_____ , _____)
Storm Check (Think, Write, Discuss, Report)
What rule for changes in coordinates would
you create for reflections across the x-axis?
A reflection across the x-axis changes the
original pre-image coordinates from (x, y) to
_______________________________________.
R x-axis(x, y)  (____ , ____)
The BLUE triangle is the PRE-IMAGE and the GREEN triangle
is the IMAGE. How would you describe the reflection?
The IMAGE has reflected across ____________.
ABC
A’B’C’
A
C
Coordinates for Point A
A’
B B’
(_____ , _____)
Coordinates for Point A’
C’
(_____ , _____)
Coordinates for Point B
(_____ , _____)
Coordinates for Point B’
(_____ , _____)
Storm Check (Think, Write, Discuss, Report)
What rule for changes in coordinates would
you create for reflections across the y-axis?
A reflection across the y-axis changes the
original pre-image coordinates from (x, y) to
_______________________________________.
R y-axis(x, y)  (____ , ____)
Reflection Vocabulary
1) Pre-Image
2) Image
3) Axis of Reflection
REFLECTION across y = x
y=x
(a, b)  (b, a)
REFLECTION (Flip): There are 4 main axes of reflection:
x-axis
(a, b)  (a, -b)
y-axis
(a, b)  (-a, b)
y=x
(a, b)  (b, a)
y = -x
(a, b)  (-b, -a)
Title: IM1 – G-CO-4 Lesson 2 Reflections
Date:
Learning Target
By the end of the period, I will create a
definition of reflection in 2 dimensions and
apply that definition to a given object.
I will demonstrate this by completing FourSquare Notes and by solving problems in a
pair/group activity.
Home Work 1-2-3:
2) Section ______
TxtBk. Problems_________
Solved and Put in Binder?
Date
1) Class 4-Square Notes Put In Binder?
3) Section ______
Notes Copied on blank sheet
of paper in Binder?
Table of Contents
Description
Date Due