Question

Dear Mitch,

A while back I read in a teacher's blog that there is a Valentine's Day Lesson you used to give for high school and middle school students that involved measuring students' heart rates, pulse, and blood pressure and how they changed when the students viewed certain types of pictures. I also heard that students thought it was one of the most interesting and entertaining lessons they'd ever experienced. If the person was correct about it being you, would you please explain a little bit about it so that I can try it with my classes? (In the mornings I teach two classes of accelerated middle school math students, and in the afternoons I'm in the high school building teaching math to ninth and tenth graders.)

Thank you,

And Happy Valentine's Day to You and Your Loved Ones,

Ms. B.

Duluth, Georgia

Answer

Dear Ms. B,

Yes, that's me!

There is no end to the possibilities for what can be done in one or two periods of math, or even an entire week's group of math classes for ANY holiday, and St. Valentine's Day is certainly as good an example as any. Regarding the specific one about which you're asking, the easiest way to do it is to acquire or borrow one of those battery-operated blood-pressure machines, which are designed for at-home use and available in almost every local pharmacy. (It should be relatively easy to find someone willing to let the class borrow one, but I think it would be even easier to convince the director of the math department of your school or district that it is a worthwhile one-time investment to be used year after year. Finally, on this point, since they range in price beginning at round $19.95 - $24.95, and accuracy is not as critical as it would be for someone who's actually using it for health purposes rather than math, it makes sense to get one of the most inexpensive ones you can find.)

O.K. Now, I'll assume you have one. Like any item to be used with a classroom, do not forget to 'play' with it a bit the night before so you can easily guide others through its use. (For example, make sure that fresh batteries are installed correctly, etc.)

In class, begin by asking for volunteers, showing them the machine. NEVER require anyone to volunteer to give their blood pressure, as it is something that is personal for anyone who feels it is personal. A student who is aware of having high blood pressure, or who smokes cigarettes, or who is substantially overweight, etc. has every right in the world not to want to unnecessarily expose such data to peers. Also, lightly but credibly stress that you are NOT a medical person and this machine is NOT known for its accuracy, because in the odd event that a student who volunteers happens to make the machine reveal concerning information, on Valentine's Day your class is not the time or the place to open such a discussion.

(By the way: See how even the simplest ideas can turn sour if you don't think through the potential problems beforehand? Believe me, every creative teacher gradually accumulates stories of lessons he/she wishes had never occurred to him!)

So, you've got the volunteers. Then you set them up with partners who take their blood pressure. (Obviously this would be the place where many teachers reading this could not help but think it would be great to have a supply of such machines, perhaps three or four, to move the activity along; and I would agree.)

There are generally two readings that show up: systolic and diastolic. I am not going to get into their meanings here, but suffice it to say that one of these is always listed over the other, i.e., 120/80, etc.

For younger grades (the middle school classes you mentioned), you might have them graph one set of the numbers with one color marker (say the diastolic), and the other set of numbers with a different color.

You might have them try to see if a constant can be found. For example, if 120/80 is one person's, and the next person's is 150/100, they might figure out a 3/2 type relationship, though I would not bet on that one.

You might have the same person's blood pressure checked three or four times, graph those, and discuss the margin of error that the machine may have, or the possible fluctuations from minute to minute for a given individual. Average the readings (or, better, of course, is to have the students obtain the average) and then, perhaps, move the class onto a discussion of standard deviation. Then, perhaps, have everyone whose pressure was measured hop up and down for three-four minutes, and then have their numbers retaken; graph each set and see what percentage/portion/fraction it changes.

Finally, most of the machines -- if not all -- also measure pulse.

Measure the pulse of a volunteer. Then discuss the visual effects of looking at certain types of pictures. Perhaps a photograph of a bull charging toward the lens can be shown, or a picture of a pleasant blue sky, or a picture of a roller coaster. Each picture should be stared at for a minute or so. Then have blood pressures/pulses rechecked, graphed, and see what effect-if any – the images had. Can a mathematically accurate formula be devised to approximate future predictions? These are just some examples. Have students come up with others. Good Luck, and have fun!

Hope this helps,

And Happy Valentine's Day!

Mitch