Dear John,
I have interspersed some remarks.
On 2011/01/23, at 11:39 , John M. Steele wrote:
> I feel I need to take issue with assertion that grams and kilograms or
> millimeters and meters are different units. The unit is the kilogram and the
> meter. The prefixes only scale units in decimal multiples and submultiples
> (they are a replacement for formally writing out scientific notation).
What you say is true but an argument along these lines does not work in any
metrication upgrade that I have ever observed. To a builder's labourer there
are millimetres, there are metres, and there are kilometres. And it takes some
time for some of these largely innumerate folk to see that:
1000 millimetres = 1 metre 1000
metres = 1 kilometre
For them this is an achievement in itself. I have never mentioned the coherence
of the metric system on any building site.
I have mentioned before that the principles that apply to metrology are not the
same as those that are useful for a successful and fast metrication upgrade.
Although to many highly numerate scientists and engineers the application of
metrology principles is considered useful for metrication programs. You could
consider the assumption about high levels of numeracy as an example of what the
Heath Brothers call the "Curse of Knowledge" where an expert operates on a
false assumption assuming it to be correct. See http://heathbrothers.com for
details of Chip and Dan Heath's book called "Made to Stick: why some ideas
survive while others die".
Hugh Mackay, in his Australian book, "What makes us tick?" is not so kind as
the Heath brothers. Hugh uses the term, "Professional deformity" instead of
"Curse of Knowledge". He writes about scientists (and engineers?) in these
terms:
… dozens of scientists might miss a particular piece of apparently obvious
evidence until one person -- perhaps coming fresh to the field -- spots what
they had all missed, because they were looking at the evidence through the
filter of their preconceptions. 'Professional deformity' is a hazard for any
highly educated person: it refers to the tendency to be blinkered by your
specialised knowledge.
> Only the unit is coherent in calculations. When combined with a prefix,
> coherence is lost (except the kilogram, where the prefix is a part of the
> unit). It is true that essentially all engineering societies use the
> convention that all dimensions are millimeters unless otherwise noted (only
> they may appear as a "naked number" without an explicit unit). However,
> engineers calculate, and the coherent unit for length in calculations is the
> meter. One absolutely must be able to convert a prefixed unit to the basic
> unit and scientific notation. Every engineer will be using only millimeters
> on drawings and only meters in calculations, hence "converting" between them.
I agree with you completely on this metrological point except for the naked
number. However, I would never try to directly use this information in a
metrication upgrade. I would have this in the back of my mind to answer
questions from more numerate trainees, but it would not form part of my "lesson
plan". Often I see a small note on a building drawing that states "All
dimensions in millimetres" and then there are multiple "naked numbers" all over
the drawing.
> I will grant that American schools go a bit overboard in how many nanometers
> are in a kilometer, and "extreme decimal shuffling;" however, one MUST be
> able to convert at least between the adjacent prefixes one is likely to
> encounter in the real world.
A problem here is the confusion between "pure mathematics" and "applied
mathematics" where the metric system is used to teach about the sliding of
decimal points backwards and forwards along a number. You don't need the metric
system to teach this skill but it seems to be a convenient application to
teachers. When we consider actual industrial applications, such as the building
and construction industry in Australia, they deliberately chose to use
millimetres ONLY and this has the effect that there are no decimal numbers and
no common or vulgar fractions on any building sites. To achieve this smoothly,
economically and quickly, we applied proven training techniques that did not
refer to meteorological principles at all. As an example we taught that volume
is measured like this:
1000 millilitres = 1 metre
1000 litres = 1 cubic metre
No attempt was made to define the litre in terms of a cubic decimetre or a
millilitre as a cubic centimetre. Sometimes we might mention that a cubic metre
of water is called a kilolitre (or a megalitre when there are multiple floods.)
As a side issue, an interesting calculation that our Australian meteorologists
and hydrologists use for rain on already saturated land is that one millimetre
of rain on one square kilometre of land will provide a run-off of one megalitre
of flood water. This calculation has been well used over the last few weeks in
Australia. I don't even think of the horrors and errors that would be involved
in a similar calculation using old pre=metric measures.
> Even in dividing or multiplying a recipe, one is likely to need to shift
> between grams and kilograms. I feel that the basic skill to shift between
> relevant prefixes is an essential metric skill, and for one to lack it, or to
> create a metrication policy which attempts to avoid it is a very poor form of
> metrication indeed.
Again what you say is true but at our house we tend to buy in kilograms and
cook in grams for the size of recipes we use for two people. We rarely use
tonnes for buying or cooking, but I have done so for a major charity barbecue.
I suppose that Australian women simply use the relationships:
1000 grams = 1 kilogram (and
very rarely) 1000 kilograms = 1 tonne
Some, more sophisticated cooks, also know the water relationship that 1 litre =
1 kilogram and so they sometimes "weigh" the liquid in their recipe rather than
dirtying a measuring jug.
> A person with a general education probably does not need to know every prefix
> from yotto to yocto, but perhaps from micro to mega, and a couple more
> depending on profession. However, if you insist people must not know more
> than one prefix for a given thing, then it is necessary to use only meters
> and kilograms to maintain a coherent set, as coherence is one of the most
> important attributes of the metric system (there is some discussion in 1.4 of
> SI Brochure).
Let me repeat, the requirements of metrology are not the needs of effective and
successful metrication upgrades. However, that said there is a need for
potential engineers and scientists to know all this detailed stuff for their
professional work, but I would not begin to teach this until upper secondary
school level in mathematics and science classes. I do not believe that this is
appropriate at any grade in primary schools or even lower grades in secondary
schools.
> Where we may agree is that one must generally use "unitized" numbers, naked
> numbers can only be used with an absolutely rigid code of how to interpret
> them.
I fully agree.
John, I know that you have far more knowledge of metrology that I will ever
have, but my direct experience and my focus is on successful metrication
upgrades and on whether they succeed or fail. I suppose that these two
approaches will continue to be in conflict but please keep correcting me when I
go wrong. It all helps.
Cheers,
Pat Naughtin
> From: Pat Naughtin <[email protected]>
> To: U.S. Metric Association <[email protected]>
> Sent: Sat, January 22, 2011 5:33:39 PM
> Subject: [USMA:49576] Re: More dumbing down via NPR
>
> As you know I have pointed out here previously that if you don't have a
> metrication policy then people will make up their own often providing two
> possible metric system units. This leads directly, in my opinion, to what the
> Heath brothers call "decision paralysis" where people do not have enough
> knowledge of the metric system to know what to do; so they revert to old
> pre-metric measuring words because they seem to be familiar (and not
> necessarily because they understand these either). Important examples are:
>
> * Human height where centimetres and metres are on offer as possible choices.
> This choice is promoted by schools who promote centimetres and the medical
> professions who promote metres for Body Mass Index (BMI). Given a choice many
> Australians say, "What's that in feet and inches?"
>
> * Baby masses where women are given a choice between grams and kilograms. Not
> knowing what to do with these, and not knowing that the use of kilograms is
> inherently unsafe for the health of the baby, their next question is "What's
> that in pounds and ounces?"; again putting the baby's health at even more
> serious risk.
>
> * The textile industries chose to use metres and centimetres as their
> preferred metric system units. These have then been divided into fractions
> such as half metres and quarter metres and (like the Apple Computer Company)
> into half centimetres and quarter centimetres. Given these choices a lot of
> women continue to use their old patterns in feet, inches, and yards and to
> train their daughters to do likewise. A few, such as fine artwork quilters,
> work in millimetres and the quality of their work shows the other quilters up
> remarkably.
>
> Insofar as the metrication of Australia is concerned, we were totally
> successful in areas that involved construction and engineering in all its
> forms (roads, electrical, construction, civil, environmental and so on) where
> the policy decision was made to use millimetres, ONLY. The metrication
> upgrade was quick easy and extremely economical (saving about 10 % of
> turnover for most companies). My estimate is that we are 90 % metric or more
> but we still have to work on the remainder. See
> http://www.metricationmatters.com/docs/CostOfNonMetrication.pdf
>
> It would be wise for the USA to look at Australian successes -- and failures
> -- as a guide to changing from "hidden metrication" to an honest an open
> "direct metrication". Done well the USA could again lead the world in honest
> and open measurement policies as they have done since the early 1780s. See
> http://www.metricationmatters.com/docs/MetricationTimeline.pdf and search for
> USA.
>
> Cheers,
>
> Pat Naughtin
> Geelong, Australia
>
> On 2011/01/23, at 08:21 , [email protected] wrote:
>
>> I am listening to NPR and Atlanta Public Media. An Australian woman is
>> describing her journey from Sydney to the protected reserve where aborigines
>> live up north (closest large city is Darwin).
>>
>> The aborigine could be heard telling the woman that they had 10 liters of
>> water just in case they break down, which was nice. But when the woman was
>> describing the height of some things she could see while trraveling in the
>> reserve, she used "feet" rather than "meters" (not even saying the height n
>> meters first).
>>
>> I'm quite sure the American producer asked her to convert to feet or else
>> the Aussie woman just assumed she needed to convert since she knew the
>> program was for an American audience.
>>
>> Too bad.... another chance to give Americans a clue that Australia is fully
>> metric was lost.
>>
>> Ezra
Pat Naughtin LCAMS
Author of the ebook, Metrication Leaders Guide, see
http://metricationmatters.com/MetricationLeadersGuideInfo.html
Hear Pat speak at: http://www.youtube.com/watch?v=_lshRAPvPZY
PO Box 305 Belmont 3216,
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Metric system consultant, writer, and speaker, Pat Naughtin, has helped
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