Angles (elementary)

Abstract

Students learn about classifying angles by their measure.

Objectives

Upon completion of this lesson, students will:

  • have learned what determines whether an angle is acute, obtuse, or right

Standards Addressed

Grade 6

  • Geometry

    • The student demonstrates conceptual understanding of similarity, congruence, symmetry, or transformations of shapes.

Grade 7

  • Geometry

    • The student demonstrates conceptual understanding of similarity, congruence, symmetry, or transformations of shapes.

Grade 8

  • Geometry

    • The student demonstrates conceptual understanding of similarity, congruence, symmetry, or transformations of shapes.

Fourth Grade

  • Geometry

    • Draw and identify lines and angles, and classify shapes by properties of their lines and angles.

  • Measurement and Data

    • Geometric measurement: understand concepts of angle and measure angles.

Seventh Grade

  • Geometry

    • Solve real-life and mathematical problems involving angle measure, area, surface area, and volume.

3rd Grade

  • Geometry

    • The student will demonstrate through the mathematical processes an understanding of the connection between the identification of basic attributes and the classification of two-dimensional shapes.

4th Grade

  • Geometry

    • Standard 4-4: The student will demonstrate through the mathematical processes an understanding of the relationship between two- and three-dimensional shapes, the use of transformations to determine congruency, and the representation of location and moveme
    • Standard 4-4: The student will demonstrate through the mathematical processes an understanding of the relationship between two- and three-dimensional shapes, the use of transformations to determine congruency, and the representation of location and movement within the first quadrant of a coordinate system.

  • Measurement

    • Standard 4-5: The student will demonstrate through the mathematical processes an understanding of elapsed time; conversions within the U.S. Customary System; and accurate, efficient, and generalizable methods of determining area.

3rd Grade

  • Geometry

    • 3.19 The student will identify and draw representations of line segments and angles, using a ruler or straightedge.

4th Grade

  • Geometry

    • 4.15.a The student will identify and draw representations of points, lines, line segments, rays, and angles, using a straightedge or ruler

5th Grade

  • Geometry

    • 5.14 The student will classify angles and triangles as right, acute, or obtuse.

  • Measurement

    • 5.13 The student will measure and draw right, acute, and obtuse angles and triangles, using appropriate tools.

Textbooks Aligned

Grade 5

  • Figuring All the Angles

    • Measuring Angles

Student Prerequisites

  • Technological: Students must be able to:
    • perform basic mouse manipulations such as point, click and drag
    • use a browser for experimenting with the activities

Teacher Preparation

The teacher will need:

  • access to a browser

Key Terms

acute angle

An angle whose measure is less than 90 degrees

obtuse angle

An angle whose measure is greater than 90 degrees

right angle

An angle of 90 degrees

Lesson Outline

  1. Focus and Review

    Review any previously learned information regarding angles.

  2. Objectives

    Let the students know what they will be doing and learning today. Say something like this:

    • Today, class, we are going to learn about angles.
    • We are going to learn about ways to classify angles:
      • Acute Angle
      • Obtuse Angle
      • Right Angle

  3. Teacher Input

    Lead the class in a short discussion about angles.

  4. Guided Practice

    • Open the Angles applet, show the students how it works, and emphasize that they can ignore the "Two angles are" drop-down menu.
    • Ask students to point out which angles are acute, obtuse, and right.
    • Show the Angles Worksheet to students and explain that they are supposed to write the names of all the angles that are acute in the acute column, etc.

  5. Independent Practice

    • Have students open the Angles Applet.
    • Have students work in pairs to complete the Angles Worksheet.
    • Remind students that they must complete at least 10 computer generated problems from the applet.

Alternate Outline

If only one computer is available, the activity can be rearranged in the following ways:

  • One computer could be connected to a projector in order to display each of the ten problems that the students would complete individually.
  • Ten different problems could be printed off to provide students with a paper reference to use while completing the worksheet.

Suggested Follow-Up

For advanced students, consider using the Angles Lesson.