Slide RUle

[mimififi]

Following on from a question I posted in parenting about my home educated child being allowed to use a calculator for her numeracy (she is 11) i wondered if I could post on here re slide rules.

I was wondering, how do you use them and is there any benefit from using them instead of a calculator....Do they offer more learning advantages than simply punching numbers into a machine, or is it a means to an ends and much of a muchness?

any thoughts?

[heathfield]

Calculators are infinitely more accurate than slide rules. Slide rules may give the larger units in a calculation, but smaller units become a matter of guess work.

Try the following - measure the length of an inch on a ruler by using the centimetre scale on another ruler. Do you get 2.54 cm? The .04 in the 2.54 becomes guesswork. Its the same problem with the marks on a slide rule.

[Gnu]

I don't think they offer any educational advantage, as the maths behind them involves indices and logarithms which are a bit advanced at 11.
The use of a calculator is fine for questions that can't be done in your head or on paper using numeracy methods. One of the main skills needed when using a calculator is to be able to estimate what the correct answer should be.

[tony1941]

The slide rule has been around a lot longer than the calculator, and has been largely kicked into touch because the use of a calculator requires little or no thought to get "the right answer". Slide rules will provide very quick answers, particularly for repetiitve clculations once set up, but the one thing they will not do is give you the position of the decimal point in the final number. (as Gnu says, they work on logarithms). I think that the occasional use of a slide rule will help to keep the brain active and force the operator to actually think about the calculation. One or two infamous space-related disasters may well have been caused by too much calculation and not enough thought. I make a point of keeping one in my desk and occasionally using it to confuse and intimidate the (much) younger engineers sitting around me. (But then, I am a fully qualified Grumpy old Engineer!)

[mimififi]

thank you for your answers, they have been very helpful.

Tony: You made me laugh out loud! I can quite imagine you doing that because my father is to a grumpy engineer and he uses things like that all the time and not just to intimidate younger engineers, just to appear cleverer than anyone really!!!! I guess it's an engineer thing. My son wants to be an engineer and he is grumpy in anticipation, hehehehehe

Seriously, thank you for your help. Maybe I will do a 'unit' into how to use a slide rule, but not use it instead of a calculator just yet.

cheers.

[tony1941]

If you want to explain the slide rule to a newcomer, start with two ordinary rulers and use them to add lengths together - eg, 2 cm on ruler 1 plus 3 cm on ruler 2 will arrive at 5 cm on ruler 1. Once this is in the brain (and, of course, subtraction), you will need to introduce powers of numbers and logarithms on a paper basis, finally revealing that if you multiply numbers by adding the logs, then you can multiply by adding the lengths of a logarithmically scaled ruler. Fait accompli!

Good luck.

[Tadpole_30]

mimififi im 21 and left school 6 years ago (then whent to collage and i studdied A-level maths) i have never even seen a slide rule, never mind used one, so i realy cant see an advantage in teaching a 11 yr old how to use one, we used sigentific calculators all through secondry school for more complicated sums, but i dont realy remember using a calculaor much in primary school.