Are These Tests Any Good? Part 1

The test is a staple of modern education, and not just at the classroom level.  Today, tests can determine which public schools a child can attend, whether or not a student graduates, which districts get state aid, and of course, which colleges might want you.

There is a movement afoot which seeks to legally tie teacher job performance to student test scores.  There’s a simple argument at the core of this movement (“If students are doing poorly on tests, then the teacher must be doing a poor job”), and a simple counterargument (“There many factors beyond a teacher’s influence that affect student test performance”), but it’s a complex issue, and it has generated much controversy.

As the debate rages on in educational, political, and media circles, one particular aspect of this issue rarely gets discussed:  test quality.  If the tests being used to evaluate students, schools, and now teachers, are ill-conceived, sloppy, and erroneous, how legitimate a measure of teaching and learning could they possibly be?

In short, few people connected to this issue seem interested in the rather important question “Are these tests any good?”

I will address this question in a series of posts that examine the New York State Math Regents Exams.  I’ll begin this series by looking at three questions from the multiple choice section of the 2011 Algebra II and Trigonometry exam.  The official test and scoring guide can be found here.

First, an algebra question:  which answer is equivalent to the given expression?

The “correct” answer, according to the scoring guide, is (1).  However the real answer is that none of these are equivalent to the original expression.  For two expressions to be equivalent, they must agree for every possible value of their variables.  Let  x = -1 and y = 1; the original expression evaluates to 2; the “correct” answer evaluates to undefined(or, if you prefer, to 2i).  The two expressions, therefore, are not equivalent.

Now consider this question about graphs:  which graph is not a function?

A simple way to determine if a graph is the graph of a function is to use the vertical line test:  if a vertical line can be drawn through the graph so that it intersects the graph more than once, then the graph is not the graph of a function.  The “correct” answer according to the scoring guide, is (3), which is indeed not a function.  But take a closer look at (2):

As the red vertical lines suggest, this graph also appears to fail the vertical line test.  Therefore it is not a function.  This question has two correct answers, only one of which was awarded credit.

Lastly, consider this question, again about graphs.

As it turns out, none of these graphs is the graph of cos^{-1}(x).  The graph in (3), the “correct” answer, is only part of the correct graph.  It is not the entire graph.  The actual graph of cos^{-1}(x) extends infinitely up and down.  (If you feel that the notation cos^{-1}(x) implies a restriction, note that none of these restrictions are correct, either).

While it may seem that some of the issues raised here are merely technicalities, keep in mind that technicalities play an important role in mathematics.  Furthermore, students who truly understand the relevant issues here might actually be at a disadvantage on these questions, wasting time sorting through these poorly-conceived problems and worrying about which answer to give.

A lot could be riding on this test: student graduations, teacher jobs, schools closings. With the stakes so high for so many, it seems like we should be paying closer attention to the question: Are these tests any good?

Math and Art: Curvefitting With Geogebra

Here is some student work from a recent project I conducted on fitting curves to images in Geogebra.  The details of the assignment can be found here, and more examples of student work can be seen on my Facebook page.

Students were asked to find pictures and use Geogebra to fit trigonometric curves to the images using transformations. Here are some of the results.

Smart Water = Smart Curves

Geogebra.Curvefit.Water.Bottle

My Good-Looking Windowsill

Geogebra.Curvefit.Windowsill

Sine of Camel Humps

Geogebra.Curvefit.Camel

Overall, I was really impressed with the creativity the students showed, and their facility with fitting these curves to the forms!  A mathematical and artistic success in my book.

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Math and Science Education: State-by-State Rankings

This report from the American Institute of Physics ranks U.S. states by their proficiency in Math and Science education:

https://www.aip.org/press_release/state_outcomes_math_science_education_reveal_big_disparities.html

The study uses student performance in physics and calculus courses (measured by various standardized exams) as well as teacher certification requirements to rate each state.

Massachusetts comes in first, with New York placing a respectable fifth.  Mississippi is dead last by a wide margin.

I originally came upon this story in the Huffington Post, and readers posted some interesting responses.  One comment compared and contrasted these rankings with the average math SAT scores for each state.  And another person remarked how closely these state rankings in math and science education align with state voter preference!

Teaching and Social Media: A Small Success

On one of those summer vacation days, full of promise and possibility, I innocently added an item to my To Do list:  start a blog and post something mathematical every day.  I saw it mostly as an intellectual exercise, one that might potentially be of use to some of my students, and I figured I’d just try it out and see where it led.  A productive waste of time, I thought.

Somewhere along the way, I started seeing, and capturing, more and more Math Photos.  Compelled to find math to think and write about, I started seeing more math around me.  People liked the photos, and my camera became a regular companion.  I began thinking more visually, more creatively.  While visiting home, I caught some light slipping through the blinds and snapped a few photos like this:

Light Trapezoid 1

A few days later, I received a message on Twitter from a digital colleague.  Jim Wilder (@wilderlab), a math and science teacher in Alabama, had shown my photos to some of his fourth-grade students.  Inspired, they went around looking for their own quadrilaterals in the shadows.  He shared this photo with me.

wilderlab student shadow

I was truly moved by this small surprise.  With barely an afterthought, I shot and posted that photo.  A fellow teacher saw it, shared it, and it’s now become a mathematical experience for a student I’ve never met.

This is just one small example of how much my professional world has changed through this process.  The impact of social media technologies on teachers and students seems virtually limitless, and it’s exciting to be a part of it in my own small way.

At the very least, it’s a productive waste of time.

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