Friday, March 19, 2010

Calculator Use Can Be Strenuous

We've started a new chapter in my Algebra 2 courses, this one on statistics. Today we learned how to calculate a standard deviation, which involves, among other calculations, determining how far from the mean each data point is--that's right, simple subtraction.

Now I'm no Luddite, I allow students to use calculators for this exercise. I did, however, want them to actually use the formula to calculate the standard deviation, not just input the data into the calculator and use its internal programming of statistics functions to come up with the "standard deve"--at least for this introductory exercise. I want the students to get an idea of where the standard deve comes from, and not be just "some number the calculator gives me".

One student asked me today if he could round off his average, presumably to a whole number, instead of entering it to however many decimal places each time--because typing all those numbers is just too strenuous.

I replied in a manner similar to this: "Let me get this straight. The calculator is doing all the calculations for you, and you don't even want to type the numbers into it?"

Perhaps I was wrong in this post, perhaps punching buttons on a calculator does qualify as a kinesthetic activity.


Forest said...

That kid's comment is a little hard to take since he is the member of the texting generation. Pushing buttons seems to be their specialty.

Elaine C. said...

My students were THRILLED when I gave them permission to use the calculator for the stats chapter.

Then they saw the formula. Now they're not so thrilled. ;)

They don't bother asking me to round anymore... my usual response is a very sweetly voiced "oh, is that too easy? Well, if you REALLY want I can change it so you do it by hand!" At which point, the rest of the class shushs the lazy one. (A variation of this also works well foe stopping complaints about homework quantities & weekend hw.)

Anonymous said...

I'm not facing the same situation as you-- stats in Algebra 2 (?!?)-- but when I teach the (algebra prerequisite) intro stats, I typically require some kind of TI-whatever graphing calculator, and actively discourage retyping numbers. Such a practice can propagate a roundoff error, and while that is admittedly not often a material concern, there are certain problems where it comes up.

It's tougher to avoid this if you just have them using a regular scientific calculator, and I don't permit graphing calculators in Algebra class, so I don't know what to tell you.

Kristeen & Keith said...

I agree with Elaine's strategy. If you have enough time to complain about the work you need MORE work! I learned that a long time ago from my tennis coach. And Elaine is right - it works like magic.