Regents Recap — January 2015: It’s True Because It’s True

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

This is question 25 from the Common Core Algebra exam.

January 2015 CC A 25

I’ve already complained about the contrived, artificial contexts for these questions (why not just ask “Is the sum of these two numbers rational or irrational?”), so I’ll ignore that for now.  What’s worth discussing here is the following sample student response provided by the state.

January 2015 CC A 25 -- Sample Response

So, why is the sum of a rational number and an irrational number irrational?  Because the sum of a rational number and an irrational number is always irrational.  This circular argument is offered as an example of a complete and correct response.

I’m not sure there’s a way to rewrite this question so that it admits a sensible answer.  That’s probably a good indication that it shouldn’t be on a high-stakes test.

As I’ve argued time and again, questions on these exams should stand as examples of proper mathematics.  But questions like this actually encourage bad habits in students, and teachers too, who are being told that this constitutes an appropriate response to this question.  This is yet another example of the danger of simply tacking on “Justify your reasoning” to a high-stakes exam question.

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Regents Recap — January 2015: Not Even Pseudo-Context

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

This is question 8 from the Integrated Algebra exam.

January 2015 IA 8Four students are playing a math game at home.  One of the math game questions asked them to write an algebraic equation.

The context of this question is utterly absurd  The question might as well have been

“Four students are taking a math test.  One of the questions asked them to write an algebraic equation.  Which student answered the test question correctly?”

Why not just ask “Which of the following is an example of an algebraic equation?”.  Maybe there are people who believe that framing questions as games, or humanizing them, will engage test-takers more, but it’s hard to believe that contrivances like this do anything but further separate students from the concepts they purport to assess.  This is another example of the negative impact these poorly-designed tests can have on students, which I discuss at length in my talk “g=4, and Other Lies the Test Told Me“.

Math teachers are familiar with the notion of pseudo-contextbut I’m not sure what I would call this.  Meta-pseudo-context?  Pseudo-meta-context?  Pseudo-pseudo-context?  Ridiculous, at the very least.

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Pinscreen Approximations

I’ve always enjoyed playing around with pinscreens, but only recently did I realize what cool mathematical concepts they display!

Pinscreen Approximation

For example, the image above shows an approximation of the volume of a hemisphere using right cylinders.  A pinscreen Riemann sum!

And the images below suggest how we might approximate the areas of a circle and a square using pinscreens.

pinscreen circle

pinscreen square

Compute the ratio of raised pins to total pins, and multiply by the total area of the pinscreen.  A pinscreen Monte Carlo method!

Any other cool math hiding in there?

 

 

Exploring Compound Interest

Go to a <a href="http://bucks.blogs.nytimes.com/2013/01/07/investing-money-plus-lots-of-time-equals-excitement/">related post</a> about a topic one blogger calls “incredibly important to share with your kids.” »My latest piece for the New York Times Learning Network is a math lesson exploring personal savings and the power of compound interest.  The piece was inspired by a new program in Illinois that creates an automatic payroll-deduction savings program for all state residents.

In addition to exploring the basic ideas of savings and compounding, students are invited to analyze the merits of this state-run program.

The automatic retirement savings program mentioned in the article is described as a zero-fiscal-cost program because it does not require any government funding to run. This is because the savers themselves pay the costs, in the form of fees to financial institutions, amounting to 0.75 percent of their total savings each year.

Have students compute the costs associated with maintaining the account for each of the typical savers they profiled in the previous activity. One way to do this is to compute 0.75 percent of the total value of the savings account each year, before interest is computed. This is an estimate of the amount that would be paid in fees that year, and thus should be subtracted from the amount in savings.

The entire piece is freely available here.  Hopefully students will get a sense of the power and value of long-term savings, and maybe ask a few good questions about the the true price of zero-fiscal-cost programs.

New York State Master Teacher Program

NYSMTPI’m happy to announce that I am now officially a member of the New York State Master Teacher Program.

The NYSMTP is designed to connect great math and science teachers from around New York State through networking, professional development, and professional service.  The program is inspired, in part, by the Math for America Master Teacher program in New York City, which I have been actively involved in for the past 9 years.

This past summer I was fortunate to attend a NYSMTP retreat in upstate New York, and I had a fantastic time.  I talked with teachers from all over the state, and learned a great deal about the many different, and similar, things going on across New York.  I also ran a workshop on using Twitter for professional development, which I think is a natural medium for connecting teachers in a program like this.

I’m looking forward to working more with great colleagues from across New York State!

 

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