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Mathline

What's Your Angle?
Measurement

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Objective

Using inductive reasoning, students will devise procedures for using a protractor to measure the number of degrees in an angle.

Overview of the Lesson

Students make estimates of the measurement of various angles created with angle wheels. They use quarter rotations and half rotations as points of reference. The angle wheels are used to create visual images of the sizes of various angles. Later, the protractor is introduced as a tool commonly used to measure the size of angles except, the students are not told how to use it. By applying a special technique using a hinged mirror, students determine the number of degrees in several angles which are printed on a worksheet. Since they now know the measurement of these angles, they use inductive reasoning skills to construct their own method for effectively using the protractor to measure angles.