8.G.A.5

Scroll Up

- 8.G.A.1Verify experimentally the properties of rotations, reflections, and translations:
- 8.G.A.2Understand 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.
- 8.G.A.3Describe the effect of dilations, translations, rotations and reflections on two-dimensional figures using coordinates.
- 8.G.A.4Understand that a two-dimensional figure is similar to another if the second can be obtained from the first by a sequence of rotations, reflections, translations, and dilations; given two similar two-dimensional figures, describe a sequence that exhibits the similarity between them.
- 8.G.A.5Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles. For example, arrange three copies of the same triangle so that the sum of the three angles appears to form a line, and give an argument in terms of transversals why this is so.

Scroll Down

## 8.G.A.5

## Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles. For example, arrange three copies of the same triangle so that the sum of the three angles appears to form a line, and give an argument in terms of transversals why this is so.

40 Lesson(s)

### PTA (Parallel Lines, Transversals and Angles)

Geometry »
Unit: Line-sanity!

Geometry »
Unit: Line-sanity!

Big Idea:

#### Students will draw and measure to discover relationships of angles formed by parallel lines cut by a transversal.

Standards:

Favorites
(21)

Resources
(20)

Reflections
(1)

### My Little Transversal: A multi-day project lesson

8th Grade Math »
Unit: Lines, Angles, and Algebraic Reasoning

8th Grade Math »
Unit: Lines, Angles, and Algebraic Reasoning

### Super Practice with Angles and Algebra

8th Grade Math »
Unit: Lines, Angles, and Algebraic Reasoning

8th Grade Math »
Unit: Lines, Angles, and Algebraic Reasoning

### Angles and Parallel Lines (Day 2 of 2)

8th Grade Math »
Unit: Congruence and Similarity

8th Grade Math »
Unit: Congruence and Similarity

### Prove interior angles of a triangle using transversals

8th Grade Math »
Unit: PARALLEL LINES, TRANSVERSALS, AND TRIANGLES

8th Grade Math »
Unit: PARALLEL LINES, TRANSVERSALS, AND TRIANGLES

### Special angle pairs

8th Grade Math »
Unit: PARALLEL LINES, TRANSVERSALS, AND TRIANGLES

8th Grade Math »
Unit: PARALLEL LINES, TRANSVERSALS, AND TRIANGLES

### The Triangle Sum Setup

8th Grade Math »
Unit: Congruence and Similarity

8th Grade Math »
Unit: Congruence and Similarity

### Transversals 1

8th Grade Math »
Unit: PARALLEL LINES, TRANSVERSALS, AND TRIANGLES

8th Grade Math »
Unit: PARALLEL LINES, TRANSVERSALS, AND TRIANGLES

### Angles and Parallel Lines (Day 1 of 2)

8th Grade Math »
Unit: Congruence and Similarity

8th Grade Math »
Unit: Congruence and Similarity

### Defining Key Angle Relationships

8th Grade Math »
Unit: Lines, Angles, and Algebraic Reasoning

8th Grade Math »
Unit: Lines, Angles, and Algebraic Reasoning

### Angles and Algebra

8th Grade Math »
Unit: Lines, Angles, and Algebraic Reasoning

8th Grade Math »
Unit: Lines, Angles, and Algebraic Reasoning

### Why Do Triangles Have 180 Degrees?

8th Grade Math »
Unit: Lines, Angles, and Algebraic Reasoning

8th Grade Math »
Unit: Lines, Angles, and Algebraic Reasoning

### Why Are Vertical Angles Equal?

8th Grade Math »
Unit: Lines, Angles, and Algebraic Reasoning

8th Grade Math »
Unit: Lines, Angles, and Algebraic Reasoning

### Arrange 3 copies to prove interior angles of triangles

8th Grade Math »
Unit: PARALLEL LINES, TRANSVERSALS, AND TRIANGLES

8th Grade Math »
Unit: PARALLEL LINES, TRANSVERSALS, AND TRIANGLES

### Discovering What it Means to be Similar Triangles

8th Grade Math »
Unit: Linear Equations in two Variables

8th Grade Math »
Unit: Linear Equations in two Variables

Common Core Math

### Kindergarten

### First Grade

### Second Grade

### Third Grade

### Fourth Grade

### Fifth Grade

### Sixth Grade

### Seventh Grade

### HS Number & Quantity

### HS Algebra

### HS Functions

### HS Geometry

### Kindergarten

### First Grade

### Second Grade

### Third Grade

### Fourth Grade

### Fifth Grade

### Sixth Grade

### Seventh Grade

### Eighth Grade

### Ninth and Tenth Grade

### Kindergarten

### First grade

### Second grade

### Third Grade

### Fourth grade

### Fifth grade

### Middle School

Kindergarten

First Grade

Second Grade

Third Grade

Fourth Grade

Fifth Grade

Sixth Grade

Seventh Grade

HS Number & Quantity

HS Algebra

HS Functions

HS Geometry

Kindergarten

First Grade

Second Grade

Third Grade

Fourth Grade

Fifth Grade

Sixth Grade

Seventh Grade

Eighth Grade

Ninth and Tenth Grade

Kindergarten

First grade

Second grade

Third Grade

Fourth grade

Fifth grade

Middle School