1. Triangles Lesson 16-8 CCSS 4.G.2
Literature Link: The Greedy Triangle by Marilyn Burns

2. MATH Essential Questions
How can lines, angles, and shapes be described, analyzed, and classified?
MATH
Essential
Questions

3. MATH Essential Questions
How are angles measured, added, and subtracted?
MATH
Essential
Questions

4. Write a division number story for this equation. 16 ÷ 2
Warm Up
Write a division number story for this equation. 16 ÷ 2

5. How are triangles different from other polygons?
Think and write
How are triangles different from other polygons?

6. In this lesson, you will identify and classify triangles.
Today’s Lesson
In this lesson, you will identify and classify triangles.
Let’s look at the Envision Video for this lesson and take the quiz.

7. There are 2 ways to classify triangles.
Types of triangles
There are 2 ways to classify triangles.
One is by their side lengths, which include equilateral, scalene, and isosceles triangles.
The other classification is based on types of angles, which are right, acute, and obtuse triangles.

8. Classifying triangles by side lengths
Equilateral triangles have three sides that are all the same length. The side lengths are EQUAL so it is equilateral.
Isosceles triangles have two sides that are the same length. There are 2 E’s in isosceles, and two sides of the triangle are the same.
Scalene triangles have no sides with the same length.

9. Practice!
Classify these triangles as equilateral, scalene, or isosceles

10. Classifying triangles by angles
Right triangles have one right angle.
Acute triangles are made of three acute angles.
Obtuse triangles have one obtuse angle.

11. Classify these triangles as right, acute, or obtuse. 1. 2. 3.
Practice!
Classify these triangles as right, acute, or obtuse

12. Classifying with both sides and angles
Classify these triangles as:
Right, Acute, or Obtuse
Scalene, Isosceles, or Equilateral

13. Your Task: Create a Poster Identify Three Types of Triangles
Draw the Triangles with a Ruler
Label & Describe the Triangles
Create a Riddle or Song to Help Someone Remember the Name of the Triangles
Create 3 Questions for a Triangle Game

14. Have fun designing your poster with a friend.
Lesson Wrap Up
In this lesson, you learned to describe and classify different types of triangles.
Have fun designing your poster with a friend.
Homework (16-8 Practice) for one “Paw Signature” and (16-8 Reteaching & Practice) if you want two “Paw Signatures.”
Website for Practice: