A protractor is marked with the 180 degrees of a semi-circle. We use it to measure angles and construct angles. Of course! Actually, this is a protractor.
That's why measurements with rulers are always approximations. When a measurement is between the tick marks, we can't be completely sure how long it is. If we want a four inch segment we start here and end here. Finally, we can draw segments of a desired length. How long is this segment? It is 5 inches long. The tick marks help us discover how long a line segment is in inches or in centimeters. Second, we can use a ruler to measure lengths. Here's the first item: a ruler! Woah! Kids, don't try this at home! So what's a ruler really good for? First off, we can use it as a straight-edge, to construct segments rays and lines.
#Compass vs protractor how to
Let's see if we can help Harry and Lloyd find out how to use a ruler, protractor, and compass. They've recently found some strange geometric tools on their journey, but they don't know how they work. Harry and Lloyd have been inching across the country at a snail's pace, collecting whatever they can find and trying to offload it on unsuspecting customers. Recommended for students who are 12 - 13 years old This video includes key concepts and vocabulary such as ruler (a tool for measuring segments and drawing segments of specific length) protractor (a tool for measuring angles and drawing angles of specific measure) and compass (a tool for creating circles and copying segments, all without measuring).īefore watching this video, you should already be familiar with segments, lines, rays, angles, units of length, degree measures, and a variety of geometric shapes.Īfter watching this video, you will be prepared to learn how to use a set square to construct a parallelogram, and how to use a compass to construct a triangle.Ĭommon Core Standard(s) in focus: 7.G.A.2Ī video intended for math students in the 7th grade Learn about the essential tools of geometry by helping Harry and Lloyd sell their wares! It concludes with creating exact copies of segments with a compass. Then you will learn to measure and sketch angles with a protractor. The lesson begins by teaching you to measure and sketch segments with a ruler. After this lesson, you will be able to use a ruler and protractor to measure segments and angles, and a compass to copy segments without measuring.
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