Dear All,
As a response to my ABC radio broadcast yesterday I received an email
from a primary school teacher (Year 4). Here is the teacher's letter
and my response.
Dear Teacher (name removed),
I have interspersed some remarks in red.
Pat,
Last night (or rather, early this morning on ABC Local Radio with
Trevor Chappell) I listened to your talk and enjoyed it.
Thank you for your kind remark.
One comment you made that particularly interested me was on body
measurements; viz. that your elbow to fingertip was 50 cm.
No, I used the length 500 millimetres from elbow to fingertip
(historically this has been called a 'cubit'). I very, very, rarely
use the metric system unit centimetres even though I know that it is a
legitimate part of the International System of Units (SI). I have only
used centimetres measure three things in the last 40 years. In each
case I used centimetres to estimate volume in cubic centimetres that I
immediately changed to millilitres. I estimated volumes of: froth on a
head of beer, the volume of a small fish tank, and the size of a stool
of faeces when I was researching digestion!
I avoid centimetres because I have observed, after 40 years of
studying the metrication process, that using centimetres simply slows
down the whole process of changing from old pre-metric measuring words
to the modern metric system dramatically. This is possibly largely due
to the fact that choosing millimetres means you never have to use
fractions – any kind of fractions become obsolete – this includes
decimal fractions and also common or vulgar fractions. See the article
at http://www.metricationmatters.com/docs/centimetresORmillimetres.pdf
for an extensive discussion of this issue. I would be delighted if you
could add any further thoughts that I could include in the discussion
in this article – you would be included under the teacher-librarian
classification. I would be especially delighted if you could point me
to any example where a metrication transition to the metric system
using centimetres has been simple, smooth, economical, and above all,
FAST!
I’ve made an analysis of the various occupations in Australia, and the
length units they prefer to use. From 117 occupations listed by the
Australian Bureau of Statistics, the results are as follows:
millimetre users – 96 occupations
Aircraft maintenance engineer (avionics), aircraft maintenance
engineer (mechanical), aircraft maintenance engineer (structures),
automotive electrician, binder and finisher, blacksmith, boat builder
and repairer, bricklayer, broadcast transmitter operator, business
machine mechanic, cabinetmaker, cable jointer, carpenter, carpenter
and joiner, communications linesperson, computing support technician,
dental technician, draftsperson, drainer, electrical engineering
technician, electrical power line tradesperson, electrician (special
class), electronic engineering technician, electronic equipment
tradesperson, electronic instrument tradesperson (special class),
electroplater, engraver, farrier, fibrous plasterer, fitter, flat
glass tradesperson, floor finisher, furniture finisher, furniture
upholsterer, gasfitter, gem cuter and polisher, general communications
tradesperson, general electrician, general electronic instrument
tradesperson, general fabrication engineering tradesperson, general
gardener, general mechanical engineering tradesperson, general
plumber, glass blower, graphic pre-press tradesperson, greenkeeper,
gunsmith, jeweller, joiner, landscape gardener, leather goods maker,
lift mechanic, locksmith, mechanical engineering technician,
mechanical services and air conditioning plumber, medical grade
shoemaker, metal casting tradesperson, metal fabricator (boilermaker),
metal machinist (first class), metal polisher, motor mechanic, optical
mechanic, painter and decorator, panel beater, patternmaker-grader
(clothing), piano maker, piano tuner, precision instrument maker and
repairer, pressure welder, printing machinist, refrigeration and air
conditioning mechanic, roof plumber, roof slater and tiler, saw maker
and repairer, screen printer, sheet metal worker (first class),
shipwright, shoemaker, sign writer, small offset printer, solid
plasterer, stonemason, surveyor, textile, clothing or footwear
mechanic, toolmaker, upholsterers and bedding tradespersons, tree
surgeon, vehicle body maker, vehicle painter, vehicle trimmer, wall
and floor tiler, watch and clock maker and repairer, welder (first
class), wood tradesperson, and wood turner.
centimetre and inch users – 12 occupations
Apparel cutter, baker, canvas goods maker, chef, cook, dressmaker,
general clothing tradesperson, nurseryperson, pastry cook, picture
framer, sail maker, and tailor.
7 occupations where length measures are relatively unimportant
Butcher, buttermaker or cheesemaker, confectioner, ladies hairdresser,
smallgoods maker, men's hairdresser, and meat tradespersons.
Summary of occupations
96 occupations use millimetres 83.5 %
12 occupations use a more or less random collection of centimetres,
feet, inches, yards and other old pre-metric measuring words 10.4 %
7 occupations use length measures but they are relatively unimportant
6.1 %
Given that more than 80 % of trades, crafts, and professions prefer
millimetres, it seems to me that there is a very high probability that
your students will use millimetres predominantly during their working
lives. Despite that, I have been involved in many training programs
where our students, after leaving school, are using millimetres for
the first time in their lives. One of our main tasks as industrial
trainers, is to un-teach all the centimetres stuff taught by teachers
in schools. Recently, I heard a senior trades person berate a junior
apprentice for measuring in centimetres; he said "centimetres! Don't
you know that c - m stands for 'children's measures' and we don't use
them on any of our jobs – next time tell me in millimetres."
I also consider that it’s best to keep it simple, and to only teach
the four prefixes: micro, milli, kilo, and mega in primary schools.
The other 16 metric prefixes need only be learned by senior students
who are studying sciences, especially subjects like astronomy and
physics.
You might also notice that nobody regularly uses decimetres,
decametres or hectometres in Australia at all. Except for the non-
preferred centimetre, the prefixes centi, deci, deca, and hecto are
essentially not used in Australian daily activities in any trade,
craft, or profession and maybe they shouldn't be taught in any detail
in schools – simply make mention of their existence. In the rare cases
where these prefixes are used, and these are rapidly becoming rarer,
these odd prefixes can soon be learnt. Certainly students shouldn't be
bothered with converting to or from them.
I have seen 200 plumbers change to the metric system in a single day.
I also observe metrication attempts that have lasted for 100 years or
more using centimetres. A classic example is the Kodak company who
changed completely to millimetres for photographic negative materials
in about 1904 and they are still struggling with their phonographic
paper division who chose centimetres in 2010. And this comes at an
enormous cost to the company – probably about 10 % of turnover every
year since 1904. I haven't made an estimate of this cost to the Kodak
company but I have estimated the cost to the USA as a whole, see http://www.metricationmatters.com/docs/CostOfNonMetrication.pdf
As a Primary school teacher I am keen to know of more facts about
our bodies. I have taught my class information like:
Our foot fits from wrist to elbow
This is too variable and of no immediate use to the student as it is
of no obvious practical use.
Try these 'handy' measurements:
width of little fingernail (mine is 10 mm)
width of all fingers (mine are 20 mm except for my little finger; it
is 15 mm)
width of hand across the knuckles (mine is 100 mm)
hand span from thumb tip to little finger tip (mine is 240 mm)
length of 'cubit' from elbow to tip of long finger (as you know, mine
is 500 mm). When I have my two longest fingers touching and my elbows
spread apart, the tips of my elbows are 1000 millimetres, or 1 metre,
apart)
And these 'footy' measurements:
Have students measure the length of their own shoes in millimetres
then use this information to estimate unknown lengths you have marked
out on the floor of a classroom or outside. Repeat this using the
student's own normal walking pace – you can do this by direct
measurement or by counting how many steps a student needs to cover a
known distance (say) 2000 millimetres inside or 5 000 millimetres
outside and then finding their own pace length by division.
Our nose fits from thumb to tip of forefinger (when they are pressed
side-by-side)
When do you ever use your nose for measuring – forget it!
Left shoulder to fingers (curled in 90 degrees) on right hand of
outstretched arm = 1m
Make sure that students know that the hand and arm placement for this
varies from person to person and from time to time until they are
fully grown.
Arm span = height (although I heard your disclaimer on that one!)
Put this as a theory to your class and ask them to check it out using
the height and arm span of their own bodies – use a whiteboard for arm
stretching measurements. Also do this first thing in the morning and
again last thing in the afternoon – most people lose height through
the course of each day as their inter-vertebral discs become
compressed – variations up to 38 millimetres during a day have been
measured.
A final one I've learnt years ago but cannot remember exactly is
that the circumference of our upper thigh = our head? Or from knee
to hip = head circumference?? Do you have any more interesting facts
like these to do with measurement/ratios on our bodies?
Read the passage from Gulliver's Travels where the good people of
Lilliput make a set of clothes for (the giant - to them) Gulliver. I
don't know if you have read Gulliver's Travels' recently, but there is
a delightful description of how the Lilliputians made a shirt and suit
for Gulliver requiring only the measure around his thumb — the rest of
the dimensions needed for the design and making of the clothes were
then calculated from that single measurement. You might like to
explore this by having students measure around their thumb in
millimetres, then doubling this to see how it fits around their wrist.
Next double the wrist measurement to get the neck size (also the
distance around the leg just above the knee) and then doubling this to
get the waist measurement. Notice how doing this in millimetres avoids
all fractions. Along the way you might notice that from elbow to wrist
is about a hand-span, and that from hip to knee is about 2 hand-spans
as is the distance from your knee to your ankle. Other observations
might be that the distance from shoulder to shoulder is close to the
length of two of your hand-spans or one of your cubits (for me this is
500 mm).
The kids love being able to put mathematical reasoning into use -
especially if it involves their bodies!
Use something like face paint to mark where a metre comes to on their
bodies (on me it is at the point of my hip bone)
Please let me know via this email, plus any additional facts and
figures that I can share with my class (Year 4).
Cheers!
--
Signed by the teacher
Cheers,
Pat Naughtin
Author of the ebook, Metrication Leaders Guide, that you can obtain
from http://metricationmatters.com/MetricationLeadersGuideInfo.html
PO Box 305 Belmont 3216,
Geelong, Australia
Phone: 61 3 5241 2008
Metric system consultant, writer, and speaker, Pat Naughtin, has
helped thousands of people and hundreds of companies upgrade to the
modern metric system smoothly, quickly, and so economically that they
now save thousands each year when buying, processing, or selling for
their businesses. Pat provides services and resources for many
different trades, crafts, and professions for commercial, industrial
and government metrication leaders in Asia, Europe, and in the USA.
Pat's clients include the Australian Government, Google, NASA, NIST,
and the metric associations of Canada, the UK, and the USA. See http://www.metricationmatters.com
for more metrication information, contact Pat at [email protected]
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