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Changing fractions to a percent?
Old 04-11-2008, 12:46 PM
 
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I am so embarassed to ask this question...so went anon.
Students had a math problem where they had to change 6/8 into a percent.

I FORGET HOW TO!!! I feel so dumb.
Can someone explain how to teach the kids how?
Thank you


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Problem
Old 04-11-2008, 12:54 PM
 
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If the denominator does not divide equally into 100 to make an equivalent fraction, then divide the denominator (8) into 6.00.
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not easy
Old 04-11-2008, 03:37 PM
 
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This is not easy for kids that are just really learning how fractions, decimals and percentages relate. There was a question like this on our state test last year (I only know because they ALL raised their hands and asked how to do it...poor kids.) Anyway, here's what was expected.

6/8 is not in simplest form. If you reduce (by dividing by 2/2) you'll get 3/4. Three fourths is one of those benchmark fractions (like 1/4, & 1/2) that our kids are supposed to be able to easily convert to a percentage (1/4=25%, 1/2=50%, 3/4=75% because of money). To actually do the math to convert it, you'd turn 3/4 into an equivalent fraction, using 100 as your new denominator. 4 must be mult. by 25 to = 100, so you need to mult. the numerator 3 by 25 as well (to be sure you are multiplying by a fraction name for 1). 3x25 =75. 75/100 is = to 75 percent (since percent means out of 100).

For some reason, the 9 & 10 year olds I teach think this is a bit complicated. Wonder why?
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Old 04-11-2008, 10:09 PM
 
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Yep, agree that it is meant to be simplified and then converted. We also did a lot of work on converting some of the more common fractions in decimals, like 1/3, 1/4, 1/5, 1/6, 1/8 and 1/10. Most of the kids did not remember that 1/8 = 12.5%, but there were a few that remembered 1/8 was 1/2 of 1/4, and 1/4 was 25%, so 1/8 must be half of that.... I was impressed they figured that out!

But, agree with other poster. I teach the kids (who all get calculators on state tests) that the line in a fraction actually signifies "divided by" so 6/8 is actually the same as 6 divided by 8, and the decimal can be found that way as well. I try to teach them many ways to find the decimals so they have options. Some kids understand one way better than another.
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Fraction to a Percent
Old 04-12-2008, 05:43 AM
 
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This is one of the first things I teach my 5th grade class because they need to find their own percentages on tests and quizzes all year.

We start off using a calculator. Simply tell them that you divide from top to bottom. 6/8 = 6 divided by 8 = They will get a decimal that we convert to a percent.

Later in the year we look at the ratio and figure out how to divide by hand. I tell them to push the top of ratio (numerator) off to create the division problem. 6/8 = 8)6 For some fun, we yell, "Timber!" when we push over the fraction. After all of the practice with the calculator, they understand how to convert the decimal easier and the whole concept is not such a big deal to them.

I strongly recommend having them do this for their own grades. The repeated practice is what solidifies the skill.


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