[Maths-Education] Ratio and Proportion

rouletg rouletg@educ.queensu.ca
Thu, 04 Oct 2001 11:16:05 -0400


In Ontario (Canada) we regularly go through these (pointless to me) 
exercises in attempting to provide "perfect" definitions for mathematical 
terms.   Our curriculum guidelines and texts have over the past 3 decades 
provided the definition:

Proportion:  a statement of equality between two ratios

To make this work with Dave's example below we need to agree that the 
statement "the proportion of goldfish is 6 out of 24" is a shorthand for:

(number of goldfish) : (number of fish) = 6:24

The Ontario definition also means that there is a proportion between the 
two triangles in Anne's example - ie. there are multiple equalities of ratios

Geoff Roulet


PS.  Now those of you in the UK can "solve" Ontario's problem of the day - 
Does a cone have any faces, vertices, or edges?  If so how many?  This 
appears to be a significant issue for our Junior (grades 4-6) grade teachers.

At 01:23 PM 10/4/01 +0100, Dave Wilson wrote:
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>Please help me to understaqnd these 2 words! I don't think that I have 
>ever been particularly bothered about them before, despite years of 
>teaching using texts with chapter titlse like Ratio and Proportion.
>
>I was looking at the NNS Key Stage 3 and read;
>
>Year 7 pupils should use read and write, spelling correctly ratio, proportion.
>
>It then goes on to say;
>
>Proportion compares part to whole
>offering examples - 24 fish in a pond, 6 are gold, 18 black .... the 
>proportion of goldfish is 6 out of 24
>
>and a page later;
>
>Ratio compares part to part
>
>
>These distinctions are not part of my understanding of the words. Am I 
>missing something? Is this something I should know? Am I being mislead in 
>terms of current usage by some hazy recollection of old Euclid/Heath usages?
>
>regards,
>--
>Dave
>Dave Wilson  (D.Wilson@mmu.ac.uk     A letter always reaches its 
>destination                 Dave@zizek.demon.co.uk)              Lacan
>http://s13a.math.aca.mmu.ac.uk
>
>
>
>
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-----------------------------------------------------------
Geoffrey Roulet
Coordinator, Centre for Mathematics, Science and Technology Education
Faculty of Education
Queen's University
Kingston, ON
K7L 3N6
Phone:    613-533-6000 ext. 74935 (Work External)
                74935 (Work Internal)
                613-531-3348 (Home)
Fax:        613-533-6584
e-mail:     rouletg@educ.queensu.ca
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