I was discussing a unit on logarithms with a friend today and he asked if seeing one of these would help my students’ understanding:

I had to admit that as I’ve never used a slide rule, I didn’t have a clue if it would help them or not. He seemed shocked (*he claimed it wasn’t my age that led him to believe I would have used one*). He thought it would be part of either my math or math ed coursework. Maple? Yep. Slide Rule? Nope.

So I’m wondering, am I the only math teacher who hasn’t used a slide rule?

Image credit: Slide Rule by Roger Smith

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I never have. I’d actually love to learn, just to be able to pull one out and calculate something on it. I think this falls in the same category as using an abacus: it’s interesting to study how it works, but certainly not something I’d expect to be part of any math or math ed curriculum.

Me neither. Though my mom used to carry one in her pocketbook, I think she stopped before I figured out what it was. I should get her to teach me while I’m home for Christmas.

My dad had a slide rule, and showed me how to use it a little bit. I have used an abacus for addition, but not much else.

I’m glad to know I’m not the only one. I think I’m going to figure out how to use one, if only to satisfy my own curiosity.

I used the slide rule back in elementary school. Totally forgot how it worked and everything. I figured the pencil was really all I needed.

I’m in favor of anything that makes math

concretefor our students.Most of them cannot ‘abstract’ successfully, yet we expect them to do it all the time. (Depending on which study you read, up to 1/3 of adults do not achieve Piaget’s ‘formal operations’ stage. This has huge implications for secondary school education…)

You may be interested in my article on the Kane Dead Reckoning Computer which is a circular slide rule used by pilots.

Oops – and I meant to mention in response to your concerns (in another post) about teaching trigonometry, that it is a great topic for a concrete, hands-on approach.

Getting students to observe, analyse and solve problems with manipulatives (including those that they build themselves) can be a really good way to go.

Good luck with it!

I asked many of the math teachers at work – none of them have ever used a slide rule either.

Zac – Thanks for the reminder about the manipulatives for trig. It’s being moved up on my to-do list over break. I’m heading over to read your article right now!

I own at least five slide rules and a couple of abacuses.

I learned the basics of how to use a slide rule whenever it was we first did logarithms in school; I guess that was probably the equivalent of grade 9 or so – we learned about Napier’s bones, learned about slide rules (I got my first one then) and learned to use log tables. Calculators were really just coming in then (this was the 70s), some people had them but they weren’t ubiquitous.

I think slide rules can be useful for directly demonstrating that adding logs corresponds to multiplication (at least if it’s explained right).

I’ve also done multiplication and division (and several other computations) using nomograms.

When I say “learned about slide rules” I mean we actually physically used them to do calculations for a few lessons.

One of the turning points when I was a kid that got me interested in learning math was when my dad gave me his old slide rule. He used it in college (getting an Electrical Engineering degree at Texas Tech) and later as an engineer for NASA working on the Apollo project. He showed me how to do basic arithmetic on it — I was only 8 or 9, so that’s all I really knew anyhow — but through playing around with it, and looking at the logarithmic and square root tick marks, I discovered the basic idea that some things change at an even rate (linearly) and some things change at uneven rates (concave up or concave down). Just the fact that some of the hash marks on the slide rule were evenly spaced and others were bunched up was enough to raise some serious questions about all this math stuff — which I finally put a language to when I took calculus ten years later.

Come to think of it, I believe that experience with the slide rule has formed my entire philosophy about studying and teaching math. My pedagogy today in college sure does look a lot like me playing with a slide rule.

I just came across this post and thought of you…