Angles

Abstract

The following lesson is designed to introduce students to acute, obtuse, and right angles. It is also designed to introduce students to vertical angles, adjacent angles, alternate interior angles and alternate exterior angles.

Objectives

Upon completion of this lesson, students will:

  • identify angles as acute, obtuse or right
  • identify pairs of angles with special relationships: vertical, adjacent, alternate interior and alternate exterior

Standards

The activities and discussions in this lesson address the following NCTM standards:

Geometry:

Analyze characteristics and properties of two- and three-dimensional geometric shapes and develop mathematical arguments about geometric relationships

  • precisely describe, classify, and understand relationships among types of two- and three-dimensional objects using their defining properties

  • understand relationships among the angles, side lengths, perimeters, areas, and volumes of similar objects

Student Prerequisites

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

    Teacher Preparation

    Students will need:

    • Access to a browser
    • pencil and paper
    • Copies of supplemental materials for the activities:

    Key Terms

    This lesson introduces students to the following terms through the included discussions:

    Lesson Outline

    1. Focus and Review

      Remind students what has been learned in previous lessons that will be pertinent to this lesson and/or have them begin to think about the words and ideas of this lesson:

      • Ask students if they remember what lines and rays are.

      • Continue by having them identify different lines in the classrooms, such as the edges of their desks, tables, or window sills.

      • Use these examples to lead into the definition of an angle as two connected rays.

    2. Objectives

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

      • Today, class, we are going to learn about different types of angles and the ways groups of angles can be related to each other.

      • We are going to use the computers to learn about angles, but please do not turn your computers on until I ask you to. I want to show you a little about this activity first.

    3. Teacher Input

      Lead the students through the discussion about angles. This discussion covers the vocabulary needed to play the activity and complete the worksheet.

      Explain to the students how to do the assignment. You should model or demonstrate it for the students, especially if they are not familiar with how to use our computer applets.

      • Open your browser to the angles activity in order to demonstrate it to the students.

      • Show students where they select their answers for the specified angle by clicking on the pop-down menu and scrolling to the correct answer.

      • Click on the "check answer" button to see if your choices are correct.

      • When the correct answers are found, click the "new angles" button to change to a new set of angles.

    4. Guided Practice

      Try another example, letting the students direct your moves.

      • If your class seems to be having a little trouble understanding the activity, do another example together, again letting the students direct your actions:

        • You might want to talk about each answer and why it is correct.

        • If needed, review one more time the discussion about angles.

    5. Independent Practice

      • If you choose to, you may pass out the Angles Worksheet.

      • Allow the students to work on their own to complete the worksheet, should you choose to provide one. Monitor the room for questions and to be sure that the students are on the correct web site.

    6. Closure

      You may wish to bring the class back together for a discussion of the findings. Once the students have been allowed to share what they found, summarize the results of the lesson.

    Alternate Outlines

    This lesson can be rearranged in several ways if there is only one available computer:

    • Lead the discussion about angles, and then have groups of students take turns using the angles activity.

    • Print out a sample set of angles from the web site, and have that be the one students use to complete the worksheet.

    Extensions

    This lesson may be followed by: