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Surf for More Math

Lesson 5 - Measuring Angles in Polygons


Use this interactive activity to encourage students to have fun on the Web while learning about measuring angles in polygons. Students can try this activity on their own or in pairs.


Identify and classify regular polygons by their angle measures.

Builds Upon

Student Book pages 202-203


Instructions for Use

Polygons allows students to measure the angles of polygons using an interactive protractor.

To use Polygons, click in the protractor button to display the protractor on the screen.

Set the number of sides for a polygon using the up and down arrows above and below the number button. Then click the number button to display the polygon. Click the up or down arrows above and below the yellow triangle button to increase or decrease the size of the polygon.

To measure the angles of the polygon, grab the protractor and drag it over the polygon. Place the center base of the protractor on any point on the polygon. Align the base of the protractor with the side length of the polygon. To rotate the protractor, drag the circle on the protractor. Measure the angle of the polygon. Move the protractor to another side of the polygon and measure another angle.

To try another polygon, change the number of sides using the arrows above and below the number button. Then click the number button.

Click the "quit" button to exit the program.