Shapes and Angles

Lesson 2

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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.

Lesson Materials

  • Template: Shapes (1 per student or small group) — See Anchor Task 1 for how to prepare this material before the lesson.
  • Blank Paper (1 sheet per student) — Ideally the paper is circular, though this isn't necessary
  • Template: Angles (1 per student or small group) — See Anchor Task 2 for how to prepare this material before the lesson.

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  • Problem Set
  • Student Handout Editor
  • Google Classrom Integration
  • Vocabulary Package

 

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 Fishtank Learning, 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 Fishtank Learning, 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

  • Problem Set

    • Problem Set Answer Key
  • Homework

    • Homework Answer Key

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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Use the following angles to answer the questions below. 

Write the letters of the shapes that are:

right angles: _____________________

acute angles: _____________________

obtuse angles: _____________________ 

straight angles: _____________________

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Additional Practice

Unit Practice

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