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

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

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

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

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

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.

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.

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.

Practice! Classify these triangles as equilateral, scalene, or isosceles. 1. 2. 3.

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

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

Classifying with both sides and angles Classify these triangles as: Right, Acute, or Obtuse Scalene, Isosceles, or Equilateral 1. 2. 3.

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

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: http://www.softschools.com/quiz_time/math/geometry/theme1.html