The Value of Vaguery, and Trying New Things

This beautiful image is this year’s testament to trying new things and giving vague directions.

math art -- student graph

At the end of every school year I challenge myself to do something brand new in each of my classes. This could take the form of new mathematical content, a new kind of project, a novel technology, or something else entirely. What’s important is that it’s something I’ve never done before.

In this year’s Calculus courses, that new thing was Sage Mathematical Software. To get students familiar with plotting in Sage, I presented them with a mundane task. I gave them code that defined a square region in the plane and asked them to play around with some of the parameters to create a new graph, which they would then post in our class forum.

Naturally, I provided an example of what they might do.

SAGE EXAMPLE BEFORE AND AFTERHaving never done this with students before, and being a novice with the software myself, I didn’t really know what to expect. I suppose I expected students to produce graphs similar to what I had done. They didn’t.

They played around with the functions, the colors, the domain and range. They inserted cotangents, exponential functions, and additional constraints. They found options for the region_plot function I didn’t know existed. I expected them to produce graphs of boring quadrilaterals, and instead, they produced beautiful, complex, and intricate contour maps like the one seen above.

This is what can happen when, instead of telling students to do A, B and C, you give them vague, open-ended directives like play around and share. More often than not, students rise to the occasion and create work that surprises and amazes. And this reminds us to keep trying new things in the classroom, if only to create opportunities for students to defy our expectations.

You can see more of the beautiful, diverse images the students created here.

How Old is the Oldest Person You Know?

The Prudential commercial that aired during Super Bowl 47 features what Steven Strogatz calls the most viewed histogram of all time.

According to the commercial people were asked the age of the oldest person they know, and their answers were plotted.  The resulting histogram is somewhat “normal” looking, and the average age is in the low 90s.

prudential histogram

The commercial’s message is clear:  “Look at how old people get!  You need to be better prepared for your retirement!  Come see a Prudential representative today.”

This is a good example of the subtle ways mathematics can be used to manipulate the opinions of the quantitatively unsophisticated.

The above histogram is intentionally designed to mislead viewers into thinking they may be significantly unprepared for retirement.  The average life expectancy in the US is around 78 years, but this number may not be shocking enough for advertisitng purposes.  So instead of life expectancy, Prudential used age of the oldest person you know, a data set whose average is about 15 years higher.

Showing a histogram that suggests people are likely to live into their 90s might motivate some viewers to head down to their local Prudential office, worried that they aren’t properly prepared for retirement.  But the data on display here isn’t really relevant, and the difference is so subtle that most people won’t notice the distinction.  In reality, the age of the oldest person you know has very little to do with how long you will live.

Imagine asking each member of a large group to name the salary of the highest-paid person they know.  The average of these responses, the average highest-known-salary, will almost certainly be much higher than the average salary of the people in the group.  It would be ridiculous to try to estimate the average salary of the group by looking at the average highest-known-salary, but in a sense, that is exactly what Prudential is doing in this commercial.

The fact that they are doing it intentionally to further their interests provides yet another example of  the vital need for quantitative literacy in today’s world.

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