I finally gave up and did the calculations in metric units, assuming the radius of the pool was one metre and the depth of the pool was one metre, finding the amount of water (and weight thereof) was quite simple in the metric system, thus, pi cubic meters ( pi tons, from volume as pi thimes radius squared times height) of water.
Mark
----- Original Message -----
From: j...@frewston.plus.com
Date: Sunday, October 13, 2013 4:25 am
Subject: [USMA:53321] RE: Presenting the metric system to the innumerate
To: "U.S. Metric Association" <usma@colostate.edu>
>
>
>
>
>
>
>
>
> Try the fish tank problem. You have a fish tank 20 in x 10 in x 10 in (easy
> numbers to start with, but then it gets complicated).
>
> How many fish can it hold on the basis of 5 fish to a gallon? (Different
> answers for UK and US gallons).
>
> How much would the tank weigh? (Ignore the weight of the empty tank.)
>
> If the shelf on which it rests can JUST support your weight, and the tank
> must weigh no more than than half your weight, what is the maximum weight of the
> tank? (Again ignore the weight of the empty tank.)
>
> I can’t even think of doing this problem in imperial/USC units.
>
> Now do it in metric.
>
> Tank is 50 cm x 20 cm x 20 cm. Fish at the rate of one fish per
> liter.
>
> Volume = 50 x 20 x 20 cm = 20 000 cm³ = 20 L = 20 fish.
>
> 20 L weighs 20 kg. I weigh 66 kg, so well within the maximum 33 kg safe
> limit.
>
> Metric wins in this kind of problem every time.
>
> John F-L
>
>
>
>
>
>
>
> Sent: Sunday, October 13, 2013 7:22 AM
> To: U.S. Metric Association
> Subject: [USMA:53320] RE: Presenting the metric system to the
> innumerate
>
>
>
>
Try
> finding the average height of the students in your class using feet and inches,
> then using metric units.
>
>
Next
> try them with a problem that a friend and I had a few years ago –what should the
> approximate diameter of a sphere be if it is to accommodate 2000 tons of water.
> (They may assume that one long ton (2240 lbs) equals one short ton (2000 lbs)
> equals one tonne). I did this problem mentally when it was presented to
> me. My reasoning was:
>
>
> One tonne of water has a mass of one cubic metre.
>
> We need to construct a sphere of volume 2000 cubic metres
>
> If we work in units of 10 metres, we need to find the radius and therefore the
> diameter of a sphere with volume 2 units.
>
>
If
> you made it simpler, by requiring a cube rather than a sphere, the answer works
> out at 10*(2)^0.333 metres or approximately 13 metres.
>
>
I
> had the answer, while my friend, who was working out the same problem had
> started off : 2000*2240/62.5 to get the volume. (BTB, I am a Brit, so used tones
> of 2240 lbs – another good reason for the metric system).
>
>
You
> might also like to warn your students about the hazards of drinking in the UK –
> our pints are larger than yours.
>
>
Martin
>
From:
> owner-u...@colostate.edu [mailto:owner-u...@colostate.edu] On Behalf Of
> Paul Rittman
> Sent: 12 October 2013 18:25
> To: U.S. Metric
> Association
> Subject: [USMA:53319] Presenting the metric system to the
> innumerate
>
>
>
I like to present
> the metric system to college students by first getting them to see the value of
> a decimalized system of accounting. I tell them that Thomas Jefferson asked
> Congress in the 1790s (as Sec of State, not as Prez) to decimalize the dollar
> when it was adopted as the nation’s currency, as opposed to the 1 pound=20
> shillings=240 pence system used by Britain. I’ve typically let them see the
> utility of this system of counting, by taking our year (2013), and asking them
> if we had 2013 pennies, how much money would we have, expressed in terms of
> dollars and cents? The exercise is designed to show people how easy it is, to
> recon 2013 pennies in blocks of 100. You don’t even have to do any
> multiplication or division, you just move the decimal and arrive at $20.13. I
> then tell them how easy it is to convert 1000 grams to kilograms, etc.
>
>
>
The last time I
> tried this, I received a shock. I had 3 students volunteer an answer, and the
> first two got it wrong. Fortunately, the third student did state that 2013 cents
> was equal to 20 dollars and 13 cents, but I was shocked that the rest of the
> class was either silent or guessed wrong. I’m wondering if this is symptomatic
> of the group of students as a whole (college freshmen). Now I’m sure that some
> knew, but simply didn’t feel like voicing their opinion in a large group of
> people; some others might have been bored (has been known to happen in
> classes!)—but I’m still thinking that quite a few didn’t know.
>
I think in the
> spring, I’ll give my students a short, anonymous survey to see if they can
> understand mathematical concepts like this.
>
But in the
> meantime, my suspicions remain strong that many adults are close to being
> innumerate, if not already there.
>
And I’m wondering
> how to present the metric system to them—to students who have no desire or
> ability to convert inches to feet to yards to miles, etc. If they don’t even
> bother with that, what difference would the metric system make to them? What
> attracted me to it was the standardization of it (there was only one kilometer,
> one gram, etc.), which made remembering statistics much easier. Of course
> students wouldn’t see this as much of an advantage.
>
But apart from the
> ease of converting among units, what other benefits can be presented to the man
> in the street?
>
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