To make angles you use the bottom part of the Protractor (shown on pages 3 and 4) to make any angle you disire.In this series of games, your students will learn to measure angles in whole-number degrees using a protractor. To measure an angle you put the rough side of the protractor down then put the vertex of the angle in the little hole in the middle, (shown on pages 3 and 4) and if the angle is acute you use the numbers on the bottom on the right but if it is acute but it is pointing to the left you use the left side and the top (shown on pages 3 and 4). They wrote: There are 2 things a Protractor does for you.
#Using a protractor manual#
They titled it The Protractor Manual (see Figure 1). Will and Pat designed their work as a pamphlet. What you do is measure and count by the lines on top of the protractor. When measuring, let’s say that it is 69 degrees. The hole is on the bottom of the protractor. wrote: You place the vertex of the angle you are measuring in the middle of the hole. But if it goes to the left you must read the top numbers.
If the angle goes to the right you must read the bottom numbers. Then you get the arrow and take it up to the number and the number that the line hits is the degree of your angle.Ĭuong and Cheryl wrote: One rule you must always remember is you must always have the bulls eye on the straight line on the bottom. If it’s obtuse you use the top line, if it’s acute you use the bottom line. First you find out if your angle is obtuse or acute. Then you find out what degree the angle is.
Then you put the dot on the vertex of the angle. Then you place the bottom line of the angle on the line of the protractor. Jenny and Sara, for example, wrote the following directions for measuring an angle: First, you make an angle. Students expressed their thinking in different ways. She listed all the words the students suggested: acute, right, obtuse, straight, degrees. You can include drawings if they will help make your directions clear.”īefore the students began, Cathy wrote protractor and angle on the overhead for their reference and asked them what other words about angles they might use.
#Using a protractor how to#
She said, “Your directions should tell how to measure angles and also how to draw angles of different sizes. Then Cathy gave them the challenge of figuring out how to use the protractors and writing directions that someone else could follow. “It may be helpful to use a right angle as a reference,” she suggested, “since you already know a right angle is ninety degrees.”Īfter a while, Cathy called the class to attention and asked the students to share what they had noticed.
When Cathy distributed protractors to her class in San Jose, California, she told the students, “The protractor is a useful tool for both measuring angles and drawing angles of specific sizes.” She asked the students to work in pairs and explore the protractors. Often they don’t see the need for the tool, so Cathy does not introduce protractors until after the students have had concrete experiences measuring angles several ways. From her past experiences teaching middle school students about angles, Cathy Humphreys knew that students often have difficulty learning how to use protractors.
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