Downside of calculators.

Posted on December 5, 2011


I don’t want to ban calculators at all — just as with reading accommodations, don’t let lack of one skill (especially but not exclusively a rote one) keep you from accessing another skill (especially but not exclusively a conceptual one). However, don’t stop developing the skills you lack.
Two experiences today speaking to hazards of calculator use.
The big one has actually happened three or four times today. One student doing factoring, the other doing roots and powers. They’re punching in the numbers and not processing them, instead of thinking “okay, is 8 a perfect cube? 2 x 2 x 2…” they’re *trying* to remember which procedure will get them the answer. Since it’s not associated with meaning, it’s harder to remember. 27 to the -2/3 power? Yes, the calculator will do it, and you can even get it to change that to a fraction, but: “I don’t think I”m going to remember that.” And, even if you could, you’d have to memorize a different procedure for problems that are applying the same principles in a different setup. So, instead, let’s talk about only using the calculator for the nibbles, not to cook your whole meal. That way, you’ve got a better chance of at least *seeing* that the cube root of 27 is 3, all the time.
Factoring works the same way with the divisibility rules. (Sadness — I’m afraid my “cloak of divisibility” game is *not* on the top of my “crank this out after finals in that Last Quiet Week” because my “WOrkshop, First Year” for test prep is on top, and there’s enough “80% done” stuff to Get Up and Out There. However. My fervent hope is to get to a production point where I *can* be posting a lesson a week.) When the students are crunching the big numbers, they end up looking at x^2 + 8xx + 16 and wondering just what factors will work…and punching in 6, 2, and 3 and finally 4…
And the truly calculator dependent soul has seen students punching in fractions on their TI30 … 2 “fraction” 4 “fraction” 7. Well, this is a TI83. We punch in 2/4/7 and have absolutely no idea that (much less why) this is not going to produce the same result.