Regents Recap — January 2014: Fill-in-the-Blank Proofs

Here is another installment in my series reviewing the NY State Regents exams in mathematics.

The January, 2014 Geometry exam included something I had not seen on a Regents exam:  a fill-in-the-blank proof.

2014 Geo Regents Proof 38

While I see some value in these kinds of problems in the teaching of two-column proofs, they shouldn’t be used on the final exam for a Geometry course.  The goal of teaching proof is for students to develop the skills necessary to construct their own proofs from scratch.  This problem reduces “proof” to a series of recall tasks.

So why not just ask the student to construct the proof from scratch?  The rubric suggests the answer to that question.

2014 Geo Regents Proof 38 Rubric

While grading an open-ended proof is hard, checking off a list of six reasons is easy!  Or so you would think.

Reports from colleagues who were grading this problem in a distributed grading center were disheartening.  In particular, there was a lot of disagreement about what constituted appropriate justification in moving from

\frac{RS}{RA} = \frac{RT}{RS}

to

(RS)^2 = RA \times RT

Apparently, teachers in the room wanted to accept “cross multiplying” as a legitimate reason, but would not accept “multiplication property of equality”.  The site supervisor agreed, despite my colleagues’ objections.

Problems like this highlight the tendency to test what is easily tested and graded, not necessarily what’s important.  And grading room stories like this should give pause to those who like to believe that these tests represent objective measures of learning or knowledge.

Math Photo: Snowy Histogram

Snowy Histogram

The way the snow collected on the fence reminded me of a histogram, though you might have to rotate your head 225 degrees to see it for yourself!  As I took this in, I wondered why some chains of snow were longer than others.  I also wondered what this representation of data said about the direction of snowfall.

Related Posts

 

Math Quiz — NYT Learning Network

oil pipelineThrough Math for America, I am part of an ongoing collaboration with the New York Times Learning Network. My latest contribution, a Test Yourself quiz-question, can be found here

Test Yourself — Math, February 12, 2014

This problem is about the proposed Keystone oil pipeline, which would transport around 830,000 barrels of oil every day from Canada to the Gulf of Mexico.  What is the approximate yearly value of the oil transported by the pipeline?

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