Math Forum Discussions

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Posts: 9
Registered: 12/4/04

Reducing Fractions
Posted: Aug 24, 2000 1:09 AM

Plain Text

I'm not sure this will work but here goes:

1. Play "prime number" game. It goes like this:
Define a prime number [one that can only be evenly divided by itself
and 1].
Have class find all the prime numbers between 1 and 10.
Then have class find all the prime numbers between 11 and 20.
Then have class review finding all the prime numbers between 1 and 20.
Then have class find all the prime numbers between 21 and 30.
Then have class review finding all the prime numbers between 1 and 30.
And so on...
Hang each prime number on poster paper around the classroom as they
are found. Visual reenforcement.

2. Play "find the factors" game. It goes like this:
Write a number on the board, start small,e.g. between 1 and 10
Have the students find the factors.
Then go for numbers between 11 to 20, just like the "prime number"
game.
Then review finding the factors of numbers between 1 and 20.
And so on...

Some of these exercizes can be done in class;some can be homework.

3. Now have the students write the factors of the numerator N and the
denominator D in a fraction N/D. Have them cancel like factors in N
and D. They just keep finding factors in N and D until all the numbers
are prime! Wow, we are just playing the "prime game".

4. You can use some "tricks" that are easy for the students to
remember and apply:

If a number in either N or D is even, it can always be written as 2*
something. If it is still even repeat the division by 2 so the number
can be written as 2*2*something and so on.

If a number ends in 5 or 0 it is always divisible by 5 (which is
prime)so that even helps more. Repeat the division by 5 again etc.

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