The Protractor Tool

25 Jun

Let’s look for and make use of structure. Which of these is not like the other?

A. SMART Notebook software protractor tool

Screen Shot 2014-06-25 at 3.15.40 PM

B. Promethean ActivInspire software protractor tool

Screen Shot 2014-06-25 at 3.16.12 PM

C. PARCC digital tool

Screen Shot 2014-06-25 at 3.18.09 PM

D. Smarter Balanced digital tool

Screen Shot 2014-06-25 at 6.21.52 PM

If you were trying to attend to precision, would you prefer one over the other?


Question 26 on the PARCC EOY Grade 4 Practice Test asks which angle measures 65˚, which I can do without using the protractor.

Screen Shot 2014-06-25 at 6.31.27 PM

But I tried using the protractor tool, just to see how it worked, and I had a difficult time using it.

Screen Shot 2014-04-14 at 2.47.32 PM

It struck me that I don’t think using the protractor tool should be tricky. We are already asking students to measure while negotiating rotating the computer protractor with a mouse or trackpad. Do we expect them to guess where the rays would extend as well? On paper, I would use my pencil and a straightedge to extend the rays.

I felt confident about placing an initial ray of an angle at 0 using the other protractor tools.

Screen Shot 2014-06-25 at 6.22.07 PM Screen Shot 2014-04-16 at 5.58.12 AM

I’d be more confident about my precision using the PARCC protractor if there were a horizontal line connecting the 0/180 measurements on both sides.  But maybe there is a trick to using the PARCC protractor tool that I don’t know? Or maybe PARCC will consider improving their tool?

And so the journey continues, wanting the best tools available for our students so that they can show they know how to use appropriate tools strategically


Posted by on June 25, 2014 in Angles & Triangles, Geometry


Tags: , , , , ,

3 responses to “The Protractor Tool

  1. goldenoj

    June 25, 2014 at 8:33 pm

    Don’t forget Jennifer Silverman’s ProRadian!

    Hopefully the PARCC won’t ask questions that this level of precision will be required if the tool has this problem.

    • jwilson828

      June 26, 2014 at 4:23 pm

      Yes! Thanks for the reminder about the ProRadian! And hopefully you are correct about the questions. I mainly wrote this because I wonder if PARCC realizes that the angle rays don’t extend to the markings or whether that might have been an oversight. All of the protractor tools are a bit different, and so it might not have been deliberate for the students to have to “eyeball” the measure while using the tool.

  2. howardat58

    July 20, 2014 at 8:47 am

    My very simple question is:
    “When does anybody need to measure an angle?”
    My simple answer is “When they have two intersecting lines on paper or as part of a real object.”
    The idea of a “Protractor tool” is too much!
    If I was a student (many days have passed since then) I would get out my protractor an hold it against the computer screen!
    The computerized protractor doesn’t fit the term “appropriate tool”.

    While I’m here can you enlighten me regarding the word “strategically”? Is it as opposed to “tactically” as in nuclear weapons?

    The question would have been better if it had said “Which of these angles is closest to 65 degrees?”


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