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Measuring angle accurately


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My dd (10yo, 4th grade) is having a terrible time measuring angles in math accurately. Today she is working on parallelograms. When she measures the 4 angles, she gets different measurements for each angle. Because of this she is not learning that the opposite angles are equal, which is a goal of the lesson. I have been making her redo and redo since we have started this chapter on geometry. I have shown her several times how to measure more precisely. We are both getting frustrated with each other over this. She doesn't get why "close enough" is not good enough. Any suggestions to help her?

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She doesn't get why "close enough" is not good enough. Any suggestions to help her?

 

Get her to draw regular pentagons or hexagons using her protractor and ruler. If she make a mistake measuring the angles, the last line would not join back to the starting point. My kids use the traditional protracter without the swing arm.

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My ds had trouble with the fine motor control necessary for accurate measuring and drawing. I'm trying to remember when those topics first came up in his math program, but they came up again and again. Anyway, I didn't push it. He did his best, and we talked about how inaccuracies could happen (width of pencil line, angle of the pencil against a straightedge, the compass/protractor slipping, etc.). He understood what the relationships *should* be, and we moved on.

 

Each time we came to geometry topics, his abilities improved, and by sixth grade he could measure and draw quite accurately.

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My ds had trouble with the fine motor control necessary for accurate measuring and drawing. I'm trying to remember when those topics first came up in his math program, but they came up again and again. Anyway, I didn't push it. He did his best, and we talked about how inaccuracies could happen (width of pencil line, angle of the pencil against a straightedge, the compass/protractor slipping, etc.). He understood what the relationships *should* be, and we moved on.

 

Each time we came to geometry topics, his abilities improved, and by sixth grade he could measure and draw quite accurately.

 

That may be what i have to do. It's hard to know when it seems the material for her age/grade expects her to do it, so you don't know if it's really ok if they can't quite get it yet.

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You could also copy the figure, cut it out, then tear of angles so she can see that the angles are the same.

You could also do the measuring with her looking over as you demonstrate.

It's also a good opportunity to discuss error of measurement :)

 

We're doing a similar exercise now. My son broke one protractor by putting it on his thumb. Sigh.

Our other protractor is more difficult to measure with, but he's managing.

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Is a protractor with a swing arm the same as a goniometer? My 5th grader uses a goniometer with RightStart and I love that tool. I can't imagine making her use a protractor after the ease of the goniometer.

 

 

It is different from a goniometer. The protractor with a swing arm looks like this http://www2.fiskars.com/Kids-Activities-School/Products/Learning-and-Classroom-Tools/Swing-Arm-Protractor#.UTV_d6a9Kc0

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