Wednesday, July 4, 2018

Math in the news
Every July 1 there will be something in the news on the New York Mets paying retired baseball player Bobby Bonilla $1.9 million per year, even though he last played for the Mets in 1999.

The Mets released him in 1999, but they still owed him $5.9 million in 2000 for the last year of a 5-year contract. The Mets and his agent negotiated a deal where the Mets would pay him 25 deferred payments of $1,193,248 per year starting in 2011 and ending in 2035. This was calculated at an 8% interest rate. The Mets were willing to do this because they thought they were earning 12% to 15% on investments with Bernie Madoff which turned out to be fictional.

From Bonilla’s viewpoint these 25 payments of $1,193,248 per year, deferred 10 years from 2001, has a present value equal to the $5.9 million he otherwise was due: (1/1.08^10) * 1193248 * (1 - 1.08^-25)/.08 equals 5.9 million, so at 8% interest this was a fair deal for him. At today’s low interest rates, 8% looks pretty high. From the Mets’ viewpoint, even if they only earned 10%, the present value is $4.2 million, which is lower than the $5.9 million they originally owed him. Of course the Mets did not earn 10% on their Madoff investment.

These formulas appear in many math and finance textbooks under the subject of math and finance. Accountants were no doubt involved in the negotiations. I just want to suggest that math and accounting are sometimes in the news.

Tuesday, July 25, 2017


A high school Social Studies teacher may have a degree in History, but may be called upon to teach Economics, Business Law, Personal Finance, Sociology, Psychology, Criminal Science, or whatever subjects fall under Social Science, despite having little or zero background in that subject. We just assume the teacher will learn what he or she needs.

A high school or college Math teacher may have a degree in Math, but that doesn't mean he or she has taken every possible Math course. College Geometry? Finite Math? Statistics? Cryptography? A Math teacher may be called upon to teach one of these, despite having little or zero background in that subject. We just assume the teacher will learn what he or she needs.

So when a small college puts Accounting in its Math department, and decides that Accounting will fulfill a student's Math requirement, is it so surprising that the college will ask a Math teacher to teach Accounting? They did, and I am.

I did take a semester of college Accounting, decades ago. I have worked in my non-academic career with accountants. And trust me, Accounting 1 is not rocket science. So I am teaching Accounting.

The part that bothers me is that unlike the claim I make when I teach Math, I do not have a passion for Accounting.

Any comments? Would you agree to teach Accounting?

Monday, January 2, 2017

Math is hard.  Although so is putting on eyeliner - not that I've done a lot of that.

Hi.  Something not discussed in my various teacher trainings is normalizing the difficulty of an exam.  In teaching a course for the first time, I borrow another teacher's exams, and then I try to create mine that seem about equal in difficulty.  But how difficult is my exam, and is it the appropriate level of difficulty?  For a gen ed community college math course, I sort of think the very best student should get close to 100, and the class average ought to be about 75.  Of course this assumes students attend nearly every class, pay attention in class, take notes in class, do the assigned homework, etc.; assumptions that have not been exactly true in my classes.  Maybe this also assumes I am a decent teacher.  I have been curving my exams about 15 points to account for the fact that maybe my exams were too hard, and I was perhaps not the most effective teacher. Hopefully I will improve my exam creation with experience and curve less in the future.

Friday, October 30, 2015

Why do I have to study math?

     “Why do I have to study math? I’ll never use it.”
      I’m sure every math teacher has heard this question. It’s not easy to answer. I have heard several possible answers, but I’m not completely satisfied with any of them. I have a somewhat different reply, which I learned from - of all people - an English teacher.
      One possible answer is how important math is in the real world. Each of us has our favorite real world problems that illustrate the importance of math. But these problems seem contrived, and are not the problems ordinary people encounter. The book When Are We Ever Gonna Have to Use This contains math examples from nearly 100 occupations, but most of these merely use arithmetic or pre-algebra.
      Another possible answer is that many occupations require math, and a student limits his future options by avoiding math. My reply is that most students are not going to choose such occupations.       A third possible answer is that math helps us to think logically. But many people who are quite logical thinkers and good problem solvers know minimal math. If the purpose is to teach logical thinking, maybe we should teach logic.
      Here is my reply, which I discovered during a team project in an education course. I was teamed with an English teacher, and we were trying to find some common ground between us. To my surprise, she explained that when she analyzes a poem, she searches for various patterns in the poem.
      Searching for patterns? As the math person, I thought I had exclusive rights on searching for patterns. But then I came to an epiphany: We’re all searching for patterns. The toddler who tries to learn which behaviors will elicit attention. The physician who tries to investigate the cause of an illness (think of the TV show “House”), who is similar to the police detective who tries to solve a series of crimes. The art critic and the movie critic. (I once heard a movie critic explain that when the major character travels across a bridge, there is about to be a personality change.) The plumber who searches for the leak. I’m sure you can think of many others.
      We are all searching for patterns in life, and we do this with our own unique lens on we how we view the world. As math people we look for quantitative patterns. It seems to me that the more tools we have to discover patterns, the richer our lives are. I think students should study math to give them one more tool in their toolbox to discover life’s patterns.

Saunders, H. 1988. When Are We Ever Gonna Have to Use This. White Plains, NY: Dale Seymour Publications.

Sunday, April 26, 2015

Math is math, except in social science

"So how are the eggs?" "Eggs are eggs." "Eggs are eggs. That is very profound. By the same token, couldn't you say fish is fish? I don't think so." 

So goes a Seinfeld dialog.  Similarly Sigmund Freud is alleged to have said, "Sometimes a cigar is just a cigar," although researchers question whether he really said it.

And by the same logic, math is math, whether it is taught in high school or college, a 2 year community college or a 4 year college, etc. Right?  I found a counter-example of this in statistics.

I recently taught an intro to statistics class in a psychology department using a statistics book for the behavioral sciences.  This book defines the sample standard deviation for descriptive purposes as SX with an N denominator while defining the sample standard deviation for inferential purposes as sX with an N-1 denominator.  I found a second statistics book for behavioral sciences that agrees with this.

Is there a recent textbook in the math or statistics world that defines the sample standard deviation with an N denominator?  I haven't seen it.  And not only will the student of this psychology class find this definition conflicts with the math world, but she will also find (and did find) it conflicts with the Excel world, not only for the Excel standard deviation function but for the Excel statistics Data Analysis add-in functions.

Why can't we all just get along?

Friday, January 24, 2014

After decades of suffering from her poor attitude toward math with her "Math class is tough!" quote which ironically was misreported by the press as "math is hard," Barbie is apparently putting her life on the line in Barbie Bungie Jumping to help students learn algebra and statistics:

This appears to be an experiment relating the distance of a jump to the number of rubber bands used, and then estimating the line of best fit.

NCTM has a lesson on this:

I guess blondes do have more fun!

Tuesday, October 15, 2013

Homer Simpson disproves Fermat's Last Theorem

Simpsons fans know that Lisa seems to know a lot of math for someone her age but Homer can also surprise us, and higher math often sneaks its way into the show. Two university professors give some references to some of the math that has been used on the show in their site, and they also link to another of their pages on the quite significant mathematical backgrounds of the Simpsons' writers.

I recently learned from another article that discusses math on the Simpsons that the writers once sneaked into an episode a counterexample to Fermat's Last Theorem. This theorem is a famous problem in the history of mathematics and states that no three positive integers a, b, and c can satisfy the equation an + bn = cn for any integer value of n > 2. The theorem was conjectured in 1637 and not proven until 1995, yet Homer writes on a blackboard a counterexample 398712 + 436512 = 447212.

Try Homer's counterexample on your calculator or spreadsheet. Read Simon Singh's article for more on the counterexample.