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Q&A #1544 |
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One activity that I have used in the past for this concept is as follows: Arrange your students in groups of two or at most three. Give each group a piece of construction paper. Have them draw a triangle (any kind of triangle that they wish) and cut it out. Then ask them to color each angle inside the triangle a different color up to a certain point. Then have them cut the angles out of the triangle. Now, ask them to put the three angles together side by side. Guess what? Those three angles side by sides make a straight angle. Straight angle is 180 degrees. Explain to your students that putting the angles side by side is just another way of adding them together. To prove to them that this works with any kind of triangle, have them draw a different kind of triangle and try the experiment over again. This activity is in a book called "Discovering Geometry" by Key Curriculum Press. As an extension, maybe you want them to learn more about triangles whose angles add up to more than 180 degrees. Such triangles exist on the sphere. You may also want to visit Triangles and Other Polygons section of the Internet Math Library located at: http://mathforum.org/library/browse/static/topic/triangle_g.html Good luck. -Roya Salehi, for the Teacher2Teacher service
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