On 2005 Oct 11 , at 4:08 AM, James J. Wentworth wrote:
I see no problem with using so-called "vulgar" fractions (1/2, 1/3, 4/5, etc.) with metric units.
Unlike James, I do see a problem.
The problem with using common fractions (also called "vulgar") is that, when they are used they invariably lead to the need to do arithmetic with them. If we need 1.5 kg of cheese for something and the grocery store has packages of 1/3 kg, 3/4 kg and 4/5 kg, what combination will give me about 1.5 kg that I need. This leads to the necessity of teaching the arithmetic of common fractions (adding, subtracting, and even mutiplying and dividing them) which is a royal pain in the butt and requires an inordinate amount of class time in our schools. Try
adding "1 and 7/16" to "3 and 5/12". (It's even hard to decide how to type those numbers; I've added the word "and" in the hope of making their meaning clear.)
Yes, I agree, that in common use there is nothing wrong with using the words half and quarter (and three quarters). Little more needs to be known that that two quarter make a half. It doesn't take an extra year of school arithmetic classes to learn that. But learning how to manipulate the plethora of other combinations of common fractions DOES take that much extra time.
Teaching metric only and omitting both Olde English units AND the common fractions associated with them would save enormous amounts of time and money and effort in our educational system. That time and money and effort could be put to better uses.
Regards,
Bill Hooper
Fernandina Beach, Florida, USA
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Make it simple; Make it Metric
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