Shapes and Angles

Lesson 2

Objective

Identify and draw right, obtuse, and acute angles. 

Common Core Standards

Core Standards

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  • 4.G.A.1 — Draw points, lines, line segments, rays, angles (right, acute, obtuse), and perpendicular and parallel lines. Identify these in two-dimensional figures.

Foundational Standards

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  • 3.G.A.1

Criteria for Success

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  1. Understand that a right angle is a square corner.
  2. Understand that an acute angle is one that is less than a right angle.
  3. Understand that an obtuse angle is one that is greater than a right angle but less than a straight angle.
  4. Understand that a straight angle is one that is formed by three points that are all on the same line.
  5. Determine whether angles are right, obtuse, or acute using a right-angle template (MP.5).
  6. Draw right, obtuse, and acute angles (MP.5, MP.6).

Tips for Teachers

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  • Note that students will later see that a right angle is the angle formed by perpendicular lines and measures 90°, more precise definitions of right angles. However, because these terms and concepts have not yet been introduced, the definition is somewhat informal for the time being.
  • Students are going to create a right-angle template in this lesson. Have students save this template for future lessons.

Remote Learning Guidance

If you need to adapt or shorten this lesson for remote learning, we suggest prioritizing Anchor Task 2 (benefits from worked example). Find more guidance on adapting our math curriculum for remote learning here.

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  • Problem Set
  • Student Handout Editor
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Anchor Tasks

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Problem 1

Sort the shapes (cut out from Template: Shapes) into groups. You may sort them any way you want and into as many groups as you want.

Guiding Questions

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References

EngageNY Mathematics Grade 4 Mathematics > Module 4 > Topic A > Lesson 2Concept Development Problem 1

Grade 4 Mathematics > Module 4 > Topic A > Lesson 2 of the New York State Common Core Mathematics Curriculum from EngageNY and Great Minds. © 2015 Great Minds. Licensed by EngageNY of the New York State Education Department under the CC BY-NC-SA 3.0 US license. Accessed Dec. 2, 2016, 5:15 p.m..

Modified by The Match Foundation, Inc.

Problem 2

Determine whether each of the angles (on Template: Angles) are less than, greater than, or equal to right angles.

Guiding Questions

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References

EngageNY Mathematics Grade 4 Mathematics > Module 4 > Topic A > Lesson 2Concept Development Problem 2

Grade 4 Mathematics > Module 4 > Topic A > Lesson 2 of the New York State Common Core Mathematics Curriculum from EngageNY and Great Minds. © 2015 Great Minds. Licensed by EngageNY of the New York State Education Department under the CC BY-NC-SA 3.0 US license. Accessed Dec. 2, 2016, 5:15 p.m..

Modified by The Match Foundation, Inc.

Problem 3

Draw an example of a right angle, an acute angle, an obtuse angle, and a straight angle.

Guiding Questions

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References

EngageNY Mathematics Grade 4 Mathematics > Module 4 > Topic A > Lesson 2Concept Development Problem 3

Grade 4 Mathematics > Module 4 > Topic A > Lesson 2 of the New York State Common Core Mathematics Curriculum from EngageNY and Great Minds. © 2015 Great Minds. Licensed by EngageNY of the New York State Education Department under the CC BY-NC-SA 3.0 US license. Accessed Dec. 2, 2016, 5:15 p.m..

Problem Set & Homework

Discussion of Problem Set

  • #1(c) and 1(f) are both right angles. Describe their position. Does the orientation of an angle determine whether it is right, acute, or obtuse?
  • In #3(a), each ray shared the same endpoint. The shared endpoint is called a vertex. Label the points on your angles in Problem 3. Identify the vertex in Problems 3(b) and 3(c) with your partner.
  • What is the difference between a straight angle and a line?
  • Where else in your environment have you seen right angles?
  • How did the right-angle template help you recognize and draw angles? How can a right-angle template help you recognize an acute angle?
  • How does the right-angle template help you visualize the interior of an angle? Where would I find the interior of an angle that I’ve drawn?
  • What does the exterior of an angle refer to?

Target Task

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Problem 1

Look at the following angles. 

       A                   B                   C               D                  E                      F                  G                H

                           

  1. Which angles are right angles?
  2. Which angles are obtuse angles?
  3. Which angles are acute angles?
  4. Which angles are straight angles?

References

EngageNY Mathematics Grade 4 Mathematics > Module 4 > Topic A > Lesson 2Exit Ticket, Question #2

Grade 4 Mathematics > Module 4 > Topic A > Lesson 2 of the New York State Common Core Mathematics Curriculum from EngageNY and Great Minds. © 2015 Great Minds. Licensed by EngageNY of the New York State Education Department under the CC BY-NC-SA 3.0 US license. Accessed Dec. 2, 2016, 5:15 p.m..

Modified by The Match Foundation, Inc.

Problem 2

Draw an additional example of each type of angle mentioned above.

  1. Right angle:
  2. Obtuse angle:
  3. Acute angle:
  4. Straight angle:

Mastery Response

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Additional Practice

Unit Practice

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