on 2005-10-11 05.19, Philip S Hall at [EMAIL PROTECTED] wrote: >> Common fractions do have some significance aside from Ye Olde English >> system, but those uses would not be common and the teaching of them >> could be relegated to more advanced courses in mathematics. It would be >> easier to teach when students had already studied algebra, for example. >> (Exceptions for the common fractions "one half" and "one quarter" could >> certainly be made without negating my arguments above.) > > Bill, > > I agree that for the purposes of measurement decimals are better than common > fractions for representing non-integral values > > However, imagine you are a math teacher and were teaching decimals. > > How would you explain to your pupils the meaning of numbers like 0.2, 4.5, > 2.342 etc > > Remember you have to do with this without resorting to common fractions.
Dear Phil Hall, Bill Hooper, and All, I wouldn't resort to common (vulgar) fractions; I would resort to the metric prefixes. If it was a cooking class: 0.2 litres would become 200 millilitres. 4.5 kilograms would become 4500 grams. A cupboard 2.342 metres wide would become 2342 millimetres so I could describe it to my builder. If it was a sewing class: 0.2 metres would become 200 millimetres. 4.5 metres would become 4500 millimetres. My new sewing room at 2.342 metres wide would need to be explained to my builder as 2342 millimetres. If it was sheetmetal class: 0.2 metres would become 200 millimetres. 4.5 kilograms of lead solder would become 4500 grams. A 2.342 metre workbench would be measured, cut, and assembled as 2342 mm. If it was a junior field athletics class: Your foot that is 0.2 metres long would become 200 millimetres. Your shot put throw of 4.5 metres sounds a lot more at 4500 millimetres. A long jump of 2.342 metres would also seem a lot longer at 2342 millimetres. > etc Notice how a wise choice of prefixes simply removes all fractions from each of these lessons. And this includes both vulgar and decimal fractions. Cheers, Pat Naughtin ASM (NSAA), LCAMS (USMA)* PO Box 305, Belmont, Geelong, Australia Phone 61 3 5241 2008 Pat Naughtin is the editor of the free online monthly newsletter, 'Metrication matters'. You can subscribe by going to http://www.metricationmatters.com/newsletter * Pat is the editor of the 'Numbers and measurement' chapter of the Australian Government Publishing Service 'Style manual for writers, editors and printers', he is an Accredited Speaking Member (ASM) with the National Speakers Association of Australia, and a Lifetime Certified Advanced Metrication Specialist (LCAMS) with the United States Metric Association. For more information go to: http://metricationmatters.com This email and its attachments are for the sole use of the addressee and may contain information that is confidential and/or legally privileged. This email and its attachments are subject to copyright and should not be partly or wholly reproduced without the consent of the copyright owner. Any unauthorised use of disclosure of this email or its attachments is prohibited. If you receive this email in error, please immediately delete it from your system and notify the sender by return email.
