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Discussion Starter #1
She is doing percentages. I know how to get the answer, but a different way than she is being taught-

here is the question:
Estimate
9% of 60.

This is the type of formula she is supposed to use:

To estimate 20% of 89:
round 89 to 90.
Find 20% of 90.
20%=20/100, or 1/5
1/5 of 90= 90/5= 18
So, 20% of 89 is about 18.

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This shouldn't be hard, but I cannot figure it out using that formula- but I can figure it out doing it the way I learned to do percentages. lol
 

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Umm..

Er...

Uhhh...

<<Glances surreptitiously at Nathan's paper>>
 

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What a dumbass formula. Back in the day, we were taught that "of" means times (x), i.e., 0.09 x 60 = 5.4%.
 

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My guess - and it's a guess - is that whichever number is the "oddest" is the one that needs to be rounded for the estimation. So in that case, since 60 is a good easy number, 9% should be rounded to 10%. In the style of the problem -

To estimate 9% of 60
Round 9% to 10%
10% = 10/100 or 1/10
1/10 of 60 is 60/10 = 6
So, 9% of 60 is about 6.

Of course, I think teaching how to get actual percentages is important, but then I guess so is the logic of being taught how to estimate quickly.

Anyone else?
 

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Discussion Starter #6
What a dumbass formula. Back in the day, we were taught that "of" means times (x), i.e., 0.09 x 60 = 5.4%.
EXACTLY! and that is my problem. I would just tell her that formula= but if she has to show her work, it'll screw up her mark, I'm afraid.
 

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Since they're estimating and based on what you posted, my guess would be:

round 9% to 10%
find 10% of 60
10%=10/100, or 1/10
1/10 of 60= 60/10= 6
So, 9% of 60 is about 6.
 

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Posted at the same time as Ursula!
 

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Discussion Starter #9
My guess - and it's a guess - is that whichever number is the "oddest" is the one that needs to be rounded for the estimation. So in that case, since 60 is a good easy number, 9% should be rounded to 10%. In the style of the problem -

To estimate 9% of 60
Round 9% to 10%
10% = 10/100 or 1/10
1/10 of 60 is 60/10 = 6
So, 9% of 60 is about 6.

Of course, I think teaching how to get actual percentages is important, but then I guess so is the logic of being taught how to estimate quickly.

Anyone else?
This was my best guess, as well?? Of course, she waits until the night before the unit quiz to tell me she doesn't understand it all.
 

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I remember hearing on the news or something that exact answers aren't required any more in math classes. And we wonder why we are behind the world when it comes to technology. :rolleyes:
 

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That's a stupid formula and it makes things way more confusing than they should be. Kids will get lost in all the work done in the meantime that they won't really understand what they're doing in the end!
 

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Sounds to me (like apparently it also does to Melissa) that the point is not to learn the real math but to understand how to estimate. Which means identifying which number(s) need to be rounded and then go from there to calculate the approximate answer. Which is actually a useful skill, though certainly not "pure" arithmatic in my book anyway.

Tell her good luck on the quiz.
 

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Still, you can estimate by rounding the 9% to 10% and use the "of = x" rule and it would be a heck of a lot easier and have less steps for the poor kids.
 

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If the kid knew his times table, he could just do 9 x 6 and place a decimal point.
 

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Okay, I'll stick my neck out and defend the practice. Actually there is a problem with kids learning all the formulas, but not learning to think about the answer so they can get a real wacked out answer and think it is right because of the formula. Grade schools are stressing estimates at every grade so kids get an eye for reasonableness so that later on they can spot errors. So for example if a kid in seventh grade does the formula incorrect and thinks that 9% of 60 is 540, he has learned to do estimates and should know he is looking for a number closer to 6 (therefore he didn't handle the decimals properly). Two of my kids are in highschool and I think do math better than me because they have trained their eye to look for an estimate when checking to see if there answer is correct. (And with one son in Geometry and one who did Calculus by 11 grade they do learn to do actual math).
 

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6th grade wasn't even THAT long ago for me, but holy crap, that is CONFUSING. They have totally messed things up!!!

I was looking at the homework that the kids I babysit for have, and it looks completely foreign to me.. I have taken college-level Calculus and calculus-based statistics and I can't even figure that stuff out..! :eek:
 

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Wow, I hope they don't teach Jake and Brandon percentages like that. I'd much rather them learn the right way and get the wrong answers than to be taught by estimations. Jake has started doing practice math tests for the state tests (MCT) this year - it's so watered down, it's not even funny. He has incredibly hard spelling tests for a 1st grader, but something as important as the basics math are made too simple (not that spelling isn't also important but that's why there's dictionaries and spell check ;) ).

He brought his test scores from last week home to be signed today. Here's a few examples.

Which is another way to write the number? 4 tens 2 ones
Answer choices: 24, 42, 40, 44

Which figure is a square?
Answer choices: pictures of a circle, triangle, rectangle, and square

Which figure has equal parts?

Answer choices: pictures of a triangle with 3 parts, circle with 3 parts, pentagon divided in half, and diamond with 3 parts

Which object could you trace to make the figure? (It's a circle)

Answer choices: pictures of a book,a round carton of oatmeal, a tissue box, or a block.

I mean, come on...way too easy stuff. Brandon can do all of that stuff, and he's in Kindergarten.
 

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Excuse me I have a BS in Mathematics and I think this formula is just that bs.

Teach the kids to figure percentages correctly. I can see teaching them 9% is close to 10% so you should be able to divide 60 by 10 and get 6. So 9% of 60 would have to be less than 6 so you know if you get 54 or 540 then you have a wrong answer but a formula like that is scary. I mean how hard is it to teach a child to look at an answer to see if it is reasonable you know that 9% of 60 cannot be 54 or 540 as it is more than 60 and you are looking for a fraction of 60.
 

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You're all talking a foreign language to me. :confused: How the hell would I know? Whenever I buy a new phone, the 1st thing I ask is "does it have a calculator?" I don't care if it will make or receive calls as long as it can do the sums for me. :rolleyes:
 

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Let's see - it "about this far" to the moon, you go "about this fast" and have "about this much fuel", you should "about get there" in "about so many days" - yeah - that's right! Start the countdown!
 
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