[Edu-sig] Re: reducing fractions
Fri, 15 Sep 2000 11:14:50 -0400
At 12:41 PM 8/14/00 -0700, Kirby Urner wrote:
>"Janet Johnson" <email@example.com> wrote:
>>I teach 6th grade and every year my students seem to have a lot of
>>difficulty with fractions, specifically, reducing or recognizing that a
>>fraction isn't reduced. I have given them many ideas on how to tell, even
>>to the point of writing out the factors for both the numerator and
>>denominator. Does anyone have any suggestions on how to get this concept
>>across to the students? Any suggestions would be greatly appreciated.
>You could unsimplify some fractions e.g. 2/3 -> 10/15
>i.e. show the inverse of what it means to "simplify".
>If 'prime number' is already a concept, you could try
>'relative prime' meaning no factors in common (i.e.
>"a fraction is in lowest terms when the numerator and
>denominator are both integers and are relative primes").
>Along these lines, I really like your idea of writing
>out the prime factors, crossing out those in common e.g.:
> 150/210 -> (3 x 5 x 2 x 5) / (7 x 3 x 2 x 5) -> 5/7
That's how my 7th grade teacher taught me to simplify fractions, and I've
never been sorry.