Sunday, July 11, 2010

Get a horse!

Slide rules still work.

There are good reasons to prefer calculators to slide rules if you're using the tools for production. I get that. There are good reasons to prefer cars to horses if you're using them for transportation, or word processors to pencils if writing a novel. Pencils and horses and slide rules all still work, as good as ever.

Why on Earth would a child use a slide rule?

They're too hard!
No, but they do require some more work, some number sense, on the part of the student. You cannot use a slide rule well if you do not what numbers mean. And many of my students do not.

Slide rules force the user to approximate numbers, to grasp significant figures, to sense numbers.

They're not accurate!
Well, um, yes, they are. Perhaps not as precise, but precise enough to get folks across the ocean in jet planes.

Calculators give shiny numbers with all kinds of digits--the answers look smart and sophisticated.

2 divided by 7 is 0.2857142, according to my calculator, 0.29 according to my slide rule, or more accurately (if not more precisely) 0.3 if I give a fig about sig figs.

With calculators, kids do not get that "2.000" means something different than "2." They might not get that with a slide rule, either, but there's no place to hide.

They need to know how to use calculators "in real life."
How long, really, does it take to master the functions available on a calculator? Functions that look impressive, but are incomprehensible to most students I work with.

(Yes, I know they can "do" problems with them, but with enough time and enough treats, I could teach a pigeon to punch in the right steps...)

I truly believe calculators should be banned in public school. Let children use abaci in elementary school, then slide rules in high school.

Obviously a child who needs to use the tool should be allowed to use it.
Just don't pretend any real understanding is happening.


Matt Guthrie said...

I get where you are coming from, but again what we have here is a failure to properly use the tool. You see, the name of the tool is "CALCULATE"-or, not "INTERPRETER". What has happened is that most people use the tool to simply calculate a correct answer. As a whole we have squeezed the type of thinking necessary to interpret the result right out of the curriculum. As a math teacher, I lament when I catch my students adding single digit numbers on a calculator. I hate it even more when the questions on the calculator active portion of our state exams barely rise above providing a correct result. Rarely are we testing for comprehension, evaluation, critical thinking, and number sense.

I rarely ever ask for a simple computational result. It's always a "why", "how", or "Explain" question where math or science. Calculators can be wonderful tools if used correctly.

doyle said...

Dear Matt,

Oh, I love my calculator--not quite as tangibly as I love my slide rules, but they do simplify my life.

I agree that the issues is misuse, but that's a huge issue. Slide rules simply cannot be misused the same way. Slide rules require some interpretation, furthering a child's brain development.

That kids need calculators to add single digits is sad, and belies their lack of number sense.

So why not just toss the tool? What in school requires the pseudo-sophistication of a calculator?

Thanks for writing!

John Spencer said...

My most recent Pencil Integration blog has a bit of a Luddite streak in it. A week on a farm will do that to you.

Incidentally, your post on yards mixed with my wife's desire to turn out backyard into "all things edible" has shifted our focus from attempting to have a lawn to letting the backyard be a hybrid mix of wild and planned / edible and pretty.

I still won't get a horse, but I think this year I'm going back to biking to work, not for the ecological or health benefits, but because of perspective.

Sorry if I turn every one of your blog posts into a public display of personal journal writing. :)

doyle said...

Dear John,

My absolute favorite response ever from a reader was that he grew his own veggies one year because of something I wrote.

Your backyard was doomed/blessed to be turned into a hybrid the day you met your future bride--you are truly blessed. But if I helped push it in any way, I'm happy. Children need to see real food. You have very, very lucky children.