1. Today, we will classify1 triangles by their attributes.
Learning Objective
Today, we will classify1 triangles by their attributes.
1 put into groups
Name __________________________
CFU
What are we going to do today?
What does classify mean? Classify means __________.
Activate (or Provide) Prior Knowledge
A triangle is a shape with three sides and three angles.
Which two triangles are the same? 1. A B C 2. A B C
CFU
Students, you already know that some triangles look the same. Triangles that are the same can sometimes be classified into groups.
Today, we will classify triangles by their attributes.

2. Sides Angles Equilateral Isosceles Scalene Right
Concept Development
Triangles can be classified by their attributes2.
The attributes of a triangle are the sides and angles.
2 features
Classifying Triangles by:
Go to
Skill Dev.
An equilateral triangle has three equal sides.
An isosceles triangle has two equal sides.
A scalene triangle has no equal sides.
Equilateral
Isosceles
Scalene
Sides
Right
A right triangle has one right angle.
3 cm
6 cm
4 cm
2 cm
5 cm
A right angle is a 90° angle.
Angles
Because of the simplicity of identifying right triangles (a yes or no answer), the skill development for the second loop (right triangles) is meant to be done on flash cards.
CFU #1 Which of the following is an equilateral triangle? How do you know?
Flashcards
Right Triangles A B
5 in
4 in
7 in
6 in
CFU #2
Which of the following is a right triangle?
How do you know?
What is the difference between an equilateral triangle and an isosceles triangle?
Which of the following is a scalene triangle? How do you know? A
8 in
9 in
6 in B
8 in
10 in
6 in
4 in
6 in A B
5 in

3. Classifying Triangles by Sides
Skill Development/Guided Practice
Classifying Triangles by Sides
An equilateral triangle has three equal sides.
An isosceles triangle has two equal sides.
A scalene triangle has no equal sides.
3 cm
6 cm
4 cm
2 cm
5 cm
Triangles can be classified by their attributes.
The attributes of a triangle are the sides and angles.
Classify triangles by their attributes.
Step #1: Look at the triangle carefully.
a. Identify3 equal sides on the triangle. (circle)
Step #2: Classify the triangle by its sides. “The triangle is a(an) ______ triangle because _______________.”
3 find
10 cm A
8 cm B
“The triangle is an equilateral triangle because it has three equal sides.”
“The triangle is an equilateral triangle because it has three equal sides.”
5 cm
7 cm C
Nothing should be written for Step #2. The classification, as well as the interpretation of the classification is meant to be done orally. D
6 cm
8 cm
“The triangle is an isosceles triangle because it has two equal sides.”
“The triangle is an isosceles triangle because it has two equal sides.”
CFU
(#1a) How did I/you identify equal sides on the triangle?
(#2) How did I/you classify the triangle by its sides?

4. Classifying Triangles by Sides
Skill Development/Guided Practice (continued)
Classifying Triangles by Sides
An equilateral triangle has three equal sides.
An isosceles triangle has two equal sides.
A scalene triangle has no equal sides.
3 cm
6 cm
4 cm
2 cm
5 cm
Triangles can be classified by their attributes.
The attributes of a triangle are the sides and angles.
Classify triangles by their attributes.
Step #1: Look at the triangle carefully.
a. Identify equal sides on the triangle. (circle)
Step #2: Classify the triangle by its sides. “The triangle is a(an) ______ triangle because _______________.”
4 in
8 in
10 in
3 cm
5 cm
7 cm E F
“The triangle is a scalene triangle because it has no equal sides.”
“The triangle is a scalene triangle because it has no equal sides.”
Return to
Concept
CFU
(#1a) How did I/you identify equal sides on the triangle?
(#2) How did I/you classify the triangle by its sides?

5. 1. Classifying triangles will help you create interesting designs.
Relevance
Triangles can be classified by their attributes.
The attributes of a triangle are the sides and angles.
1. Classifying triangles will help you create interesting designs.
Triangles in paintings.
Triangles in buildings.
2. Classifying triangles will help you do well on tests.
CFU
Does anyone else have another reason why it is relevant to classify triangles by their attributes? (pair-share) Why is it relevant to classify triangles by their attributes? You may give me one of my reasons or one of your own. Which reason is more relevant to you? Why?

6. Classifying Triangles by Sides
Triangles can be classified by their attributes.
Classifying Triangles by Sides
An equilateral triangle has three equal sides.
An isosceles triangle has two equal sides.
A scalene triangle has no equal sides.
3 cm
6 cm
4 cm
2 cm
5 cm
The attributes of a triangle are the sides and angles.
Skill Closure
Classify triangles by their attributes.
Step #1: Look at the triangle carefully.
a. Identify equal sides on the triangle. (circle)
Step #2: Classify the triangle by its sides. “The triangle is a(an) ______ triangle because _______________.”
7 cm A B
5 cm
9 cm
“The triangle is an isosceles triangle because it has two equal sides.”
“The triangle is an equilateral triangle because it has three equal sides.”
Constructed Response Closure
2 in ?
What is the missing side length that will make the triangle an equilateral triangle?
How do you know?
Summary Closure
What did you learn today about classifying triangles by their attributes? (pair-share)

7. Classifying Triangles by Sides
Independent Practice
Name ________________________
Triangles can be classified by their attributes.
Classifying Triangles by Sides
An equilateral triangle has three equal sides.
An isosceles triangle has two equal sides.
A scalene triangle has no equal sides.
3 cm
6 cm
4 cm
2 cm
5 cm
The attributes of a triangle are the sides and angles.
Classify triangles by their attributes.
Step #1: Look at the triangle carefully.
a. Identify equal sides on the triangle. (circle)
Step #2: Classify the triangle by its sides. “The triangle is a(an) ______ triangle because _______________.” A B
8 cm
6 cm
4 cm
“The triangle is an equilateral triangle because it has three equal sides.”
“The triangle is an isosceles triangle because it has two equal sides.” C
10 cm
9 cm
8 cm
“The triangle is a scalene triangle because it has no equal sides.”

8. Classifying Triangles by Sides
Periodic Review 1
Name ________________________
Triangles can be classified by their attributes.
Classifying Triangles by Sides
An equilateral triangle has three equal sides.
An isosceles triangle has two equal sides.
A scalene triangle has no equal sides.
3 cm
6 cm
4 cm
2 cm
5 cm
The attributes of a triangle are the sides and angles.
Classify triangles by their attributes.
Step #1: Look at the triangle carefully.
a. Identify equal sides on the triangle. (circle)
Step #2: Classify the triangle by its sides. “The triangle is a(an) ______ triangle because _______________.” A B
12 cm
36 in
15 in
39 in
“The triangle is a scalene triangle because it has no equal sides.”
“The triangle is an equilateral triangle because it has three equal sides.”
8 in
12 in
14 in
2 cm
3 cm C D
“The triangle is a scalene triangle because it has no equal sides.”
“The triangle is an isosceles triangle because it has two equal sides.”

9. Classifying Triangles by Sides
Periodic Review 2
Name ________________________
Triangles can be classified by their attributes.
Classifying Triangles by Sides
An equilateral triangle has three equal sides.
An isosceles triangle has two equal sides.
A scalene triangle has no equal sides.
3 cm
6 cm
4 cm
2 cm
5 cm
The attributes of a triangle are the sides and angles.
Classify triangles by their attributes.
Step #1: Look at the triangle carefully.
a. Identify equal sides on the triangle. (circle)
Step #2: Classify the triangle by its sides. “The triangle is a(an) ______ triangle because _______________.” A B
8 in
4 in
6 in
7 cm
10 cm
“The triangle is an isosceles triangle because it has two equal sides.”
“The triangle is a scalene triangle because it has no equal sides.”
4 in
20 cm
28 cm C D
“The triangle is an equilateral triangle because it has three equal sides.”
“The triangle is an isosceles triangle because it has two equal sides.”

10. Classifying Triangles by Sides
Periodic Review 3
Name ________________________
Triangles can be classified by their attributes.
Classifying Triangles by Sides
An equilateral triangle has three equal sides.
An isosceles triangle has two equal sides.
A scalene triangle has no equal sides.
3 cm
6 cm
4 cm
2 cm
5 cm
The attributes of a triangle are the sides and angles.
Classify triangles by their attributes.
Step #1: Look at the triangle carefully.
a. Identify equal sides on the triangle. (circle)
Step #2: Classify the triangle by its sides. “The triangle is a(an) ______ triangle because _______________.” A B
25 cm
16 in
“The triangle is an equilateral triangle because it has three equal sides.”
“The triangle is an equilateral triangle because it has three equal sides.”
14 cm
22 cm
9 in
5 in
7 in C D
“The triangle is an isosceles triangle because it has two equal sides.”
“The triangle is a scalene triangle because it has no equal sides.”

11. Is the triangle a right triangle?
Flashcards (Right Triangles)
Triangles can be classified by their attributes.
Right Triangle
The attributes of a triangle are the sides and angles.
A right triangle has one right angle.
A right angle is a 90° angle.
Teacher with CFU
Is the triangle a right triangle?
How did I know if the triangle was a right triangle?

12. Is the triangle a right triangle?
Flashcards (Right Triangles)
Triangles can be classified by their attributes.
Right Triangle
The attributes of a triangle are the sides and angles.
A right triangle has one right angle.
A right angle is a 90° angle.
Student with CFU
Is the triangle a right triangle?
How did you know if the triangle was a right triangle?

13. Is the triangle a right triangle?
Flashcards (Right Triangles)
Triangles can be classified by their attributes.
Right Triangle
The attributes of a triangle are the sides and angles.
A right triangle has one right angle.
A right angle is a 90° angle.
Teacher with CFU
Is the triangle a right triangle?
How did I know if the triangle was a right triangle?

14. Is the triangle a right triangle?
Flashcards (Right Triangles)
Triangles can be classified by their attributes.
Right Triangle
The attributes of a triangle are the sides and angles.
A right triangle has one right angle.
A right angle is a 90° angle.
Student with CFU
Is the triangle a right triangle?
How did you know if the triangle was a right triangle?

15. Is the triangle a right triangle?
Flashcards (Right Triangles)
Triangles can be classified by their attributes.
Right Triangle
The attributes of a triangle are the sides and angles.
A right triangle has one right angle.
A right angle is a 90° angle.
Student
Is the triangle a right triangle?

16. Is the triangle a right triangle?
Flashcards (Right Triangles)
Triangles can be classified by their attributes.
Right Triangle
The attributes of a triangle are the sides and angles.
A right triangle has one right angle.
A right angle is a 90° angle.
Student
Is the triangle a right triangle?

17. Is the triangle a right triangle?
Flashcards (Right Triangles)
Triangles can be classified by their attributes.
Right Triangle
The attributes of a triangle are the sides and angles.
A right triangle has one right angle.
A right angle is a 90° angle.
Student
Is the triangle a right triangle?

18. Is the triangle a right triangle?
Flashcards (Right Triangles)
Triangles can be classified by their attributes.
Right Triangle
The attributes of a triangle are the sides and angles.
Return to Concept
A right triangle has one right angle.
A right angle is a 90° angle.
Student with CFU
Is the triangle a right triangle?
How did you know if the triangle was a right triangle?

19. Content Access Strategies
EDI – Cognitive, Teaching and English Learners Strategies
Learning Objective : Classify triangles by their attributes.
Cognitive Strategies
Teaching Strategies
Elaboration
Demonstration
Targeted vocabulary: classify, triangles, attributes, equilateral, isosceles, scalene, right, right angle, identify
Language Strategies
Vocabulary Words
Academic
classify, identify
Content
triangles, attributes
Support
equilateral, isosceles, scalene, right, right angle
Vocabulary
Strategy
Multiple-Meaning
right
Synonym
Definition
classify, identify, equilateral, isosceles, scalene, right angle
Homophone
Internal Context Clue
Listen, Speak
Similar Sounds
Read
Tracked Reading
Decoding Rules
Write
Writing
Content Access Strategies
Comprehensible Input
Cognates
Contextual Clues
Graphic Organizer
Contextualized Definitions
Pictures

20. Blank Page