Another Example of How Common Core Confuses People
- Thread starter JimBowie1958
- Start date
Zoom-boing
Platinum Member
For teaching subtraction it's nothing short of ridiculous,imo. Seriously. But notice how they did it, they literally counted back up to the 32. I tried several times to explain this to my oldest and she just wasn't getting it, until she was forced to do so using money in the real world at work. When it "clicked" she was like ah! it's so easy! lol
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OohPooPahDoo
Gold Member
Theory?
Have you ever been to a store?
Have you ever heard a cashier count change?
Cahiers start from the subtrahend and ADD up until they reach the subtrahend.
THIS IS EXACTLY WHAT A CASHIER DOES EVERYTIME THEY COUNT CHANGE TO YOU, YA ******* IDIOT.
When you want to do 1000-99 in your head, do you actually line columns and borrow 1's ? I just add 1 + 900=901. That's the "theoretical" way of going it I suppose.
OohPooPahDoo
Gold Member
You want to lock up the person who invented counting forward?
OohPooPahDoo
Gold Member
THis is actually counting forward, not backwarsd. You count from 12 to 32.
I have no idea why we should wait till they are older to show them how to do subtraction in their head. The column method you show above is best suited to computers.
So 32-12 = 20 because....
12 + 3 = 15
15+5 = 20
20+10 = 30
30+2 = 32.
3+5+10+2 = 20.
I guess I would need a tutor. I have no clue as to why you would 'arbitrarily' ? choose to add 3 to 12 to reach 15. It would never occur to me. Stuck in the Stone Age--I guess.
I can grasp 10's--which according to another article on CC is the premise.
I believe one of the designers of CC said that 'curriculums vary'--the example he addressed was so confusing he wouldn't have included it.
ie---<Not surprisingly, the post was brought to the attention of one of the authors of the Common Core standards for mathematics, Bill McCallum of the University of Arizona. McCallum responded to the Facebook post in a recent blog entry. He states:
"So, this Common Core problem has been making the rounds. In it a student is asked to correct a number line method of subtraction, and the parent is basically saying why not do it the good old fashioned way? Of the two methods, the only one that is required by the Common Core is the parent's way:
4.NBT.4. Fluently add and subtract multi-digit whole numbers using the standard algorithm.
No previous state standards, including Indiana's, had such an explicit requirement for fluency with the standard algorithm. Now that Indiana has opted out of the Common Core, this parent had better hope they do not drop this requirement.
It is true that the standards also require students to understand place value, which I take as the goal of this problem. But there are many other ways to do that."
>
http://hechingerreport.org/content/...spond-problematic-math-quiz-went-viral_15361/
12 + 3 = 15
15+5 = 20
20+10 = 30
30+2 = 32.
3+5+10+2 = 20.
I guess I would need a tutor. I have no clue as to why you would 'arbitrarily' ? choose to add 3 to 12 to reach 15. It would never occur to me. Stuck in the Stone Age--I guess.
I can grasp 10's--which according to another article on CC is the premise.
I believe one of the designers of CC said that 'curriculums vary'--the example he addressed was so confusing he wouldn't have included it.
ie---<Not surprisingly, the post was brought to the attention of one of the authors of the Common Core standards for mathematics, Bill McCallum of the University of Arizona. McCallum responded to the Facebook post in a recent blog entry. He states:
"So, this Common Core problem has been making the rounds. In it a student is asked to correct a number line method of subtraction, and the parent is basically saying why not do it the good old fashioned way? Of the two methods, the only one that is required by the Common Core is the parent's way:
4.NBT.4. Fluently add and subtract multi-digit whole numbers using the standard algorithm.
No previous state standards, including Indiana's, had such an explicit requirement for fluency with the standard algorithm. Now that Indiana has opted out of the Common Core, this parent had better hope they do not drop this requirement.
It is true that the standards also require students to understand place value, which I take as the goal of this problem. But there are many other ways to do that."
>
http://hechingerreport.org/content/...spond-problematic-math-quiz-went-viral_15361/
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strange-4th grade math worksheet. Perhaps additional discussion is provided in class. The blocks didn't show up--fwiw. shaking my head--glad I was able to grasp addition and subtraction somehow.
Name: ________________________ Date ____________
Tons of Free Math Worksheets at: © Math Worksheets Land - Tons of Printable Math Worksheets From All Grade Levels
Decomposing Numbers Step-by-Step Lesson
1. Which picture shows that 5 + 3 = 8?
a) c)
b) d)
Answering # 1: The model that we are looking for has to have 3 key parts:
1) a piece composed of 5 parts.
2) a piece composed of 3 parts.
3) have a total number of 8 parts.
Looking at the pictures above, we can see that the parts are made of gray
and white blocks. Now we need to find a model that matches.
Looking at a we can see that it meets the pattern.
Counts of Colors 1 2 3 4 5 1 2 3
5 white blocks 3 gray blocks
Total Number of Blocks = 8 blocks
1 2 3 4 5 6 7 8
2. How do you make 8?
a) 5 + 4 c) 6 + 2
b) 4 + 3 d) 3 + 3
Name: ________________________ Date ____________
Tons of Free Math Worksheets at: © Math Worksheets Land - Tons of Printable Math Worksheets From All Grade Levels
Decomposing Numbers Step-by-Step Lesson
1. Which picture shows that 5 + 3 = 8?
a) c)
b) d)
Answering # 1: The model that we are looking for has to have 3 key parts:
1) a piece composed of 5 parts.
2) a piece composed of 3 parts.
3) have a total number of 8 parts.
Looking at the pictures above, we can see that the parts are made of gray
and white blocks. Now we need to find a model that matches.
Looking at a we can see that it meets the pattern.
Counts of Colors 1 2 3 4 5 1 2 3
5 white blocks 3 gray blocks
Total Number of Blocks = 8 blocks
1 2 3 4 5 6 7 8
2. How do you make 8?
a) 5 + 4 c) 6 + 2
b) 4 + 3 d) 3 + 3
Mr. H.
Diamond Member
The Professor
Diamond Member
- Mar 4, 2011
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OK, it's time for one of the Professor's favorite math tricks.
RULE: To square any number ending in 5, forget the five and multiply the remaining number by one number higher than itself, and then put the number 25 after the product. To square 125 we follow the simple rules:
1. Forget the last five and multiply 12 X 13 to get 156 (you know that a gross is 144 so just add another 12 to get 156).
2. Adding 25 to the end of 156 gives 15625 or 15,625.
Now that we know the rule, we can easily square 1,255 in our heads using the same method.
1. Forget the last five and multiply the remaining number (125) by one number higher than itself (126). This is the same thing as squaring 125 and adding 125 to the product.
2. We already know that 125 squared = 15, 625 so we just add another 12 5 to that number and to get 15,750.
3. Now add the number 25 to the end of 15750 to get 1575025 or 1,575,025.
This is one of the many math shortcuts I learned in the fifth grade. I doubt they teach kids things like this anymore. Those of you who know algebra know why the rule works:
If you square 85 and I square 8.5 we will get the same answer except that mine will have two decimal points. Now 8.5 is the same as 8 plus .5, so I elect to square the quantity (8 plus .5) because it's easier. To make it even easier, I will represent the number 8 by the letter X and the number .5 by Y.
Now algebraically the quantity (X + Y) squared will always yield (X² + 2XY + Y²). Replacing Y with .5 yields [X² + 2X(.5) + .5² ] or (X² + X + .25).
Factoring ( X² + X + .25) we get X(X + 1) +.25.
Therefore, 8.5 squared = 8 X 9 + .25 or 72.25.
Removing the decimal points gives 7,225.
OK, I'm outta here.
RULE: To square any number ending in 5, forget the five and multiply the remaining number by one number higher than itself, and then put the number 25 after the product. To square 125 we follow the simple rules:
1. Forget the last five and multiply 12 X 13 to get 156 (you know that a gross is 144 so just add another 12 to get 156).
2. Adding 25 to the end of 156 gives 15625 or 15,625.
Now that we know the rule, we can easily square 1,255 in our heads using the same method.
1. Forget the last five and multiply the remaining number (125) by one number higher than itself (126). This is the same thing as squaring 125 and adding 125 to the product.
2. We already know that 125 squared = 15, 625 so we just add another 12 5 to that number and to get 15,750.
3. Now add the number 25 to the end of 15750 to get 1575025 or 1,575,025.
This is one of the many math shortcuts I learned in the fifth grade. I doubt they teach kids things like this anymore. Those of you who know algebra know why the rule works:
If you square 85 and I square 8.5 we will get the same answer except that mine will have two decimal points. Now 8.5 is the same as 8 plus .5, so I elect to square the quantity (8 plus .5) because it's easier. To make it even easier, I will represent the number 8 by the letter X and the number .5 by Y.
Now algebraically the quantity (X + Y) squared will always yield (X² + 2XY + Y²). Replacing Y with .5 yields [X² + 2X(.5) + .5² ] or (X² + X + .25).
Factoring ( X² + X + .25) we get X(X + 1) +.25.
Therefore, 8.5 squared = 8 X 9 + .25 or 72.25.
Removing the decimal points gives 7,225.
OK, I'm outta here.
Zoom-boing
Platinum Member
I didn't say counting backward, I said counting back. When you're giving change it's counting back up to what they gave you. In the vid they are counting back up to the original number. Call it counting forward, it's the same thing just different phrasing.
?? The vid method makes it harder to do subtraction in your head.
7 year olds need to learn math with pencil and paper not in their heads. What I showed is how you write it on paper then teach them how to subtract/add.
Zoom-boing
Platinum Member
Well that's just it. Kids and younger people today don't learn how to 'count back/count forward' and most of them have no idea how to do this. The register gives them the amount to give back to the customer. If the register freezes they just stand there stupified. No kidding. They cannot figure out what the change back to the customer is without pencil/paper or a calculator.
My daughter is a GSA at Target and the vast majority of the cashiers have zero clue how to do this. If a customer gives them $20.02 cash for a $15.02 bill, most of them need a calculator to figure out that the change is $5. Seriously. Completely forget about giving the extra change, like if the bill is $3.76 and the customer gives you $5.01. Uh, they stare at you like zombies. And forget figuring percentages. The cashiers are to ask if the customer wants a red card (Target's debit card). They are to say 'you can save 10% off of your purchase today if you open one' But again, the vast majority if they needed to give what that percent actually is? No freaking clue. They need a calculator (and some can't even figure it out then!). It's sad really. I see this all over, not just at Target. This is coming from someone who is sucky at math! ... but even I can do this basic stuff without assistance. Why? Because I was taught it when I was a kid.
Zoom-boing
Platinum Member
It isn't an arbitrary number. Adding 3 to 12 gives you 15, which then makes it easier to 'count back' 5 more to 20, 10 more to 30, plus 2.
I understand what they're trying to do but they need to teach math the most basic and simplest way so kids have a true understanding of how to do it of how it all works. The most basic and simplest way works for most people. Then if they want to show alternative methods that's ok. But also the age of the kids they are teaching comes into play. Some of this cc stuff is abstract and little kids (6-10 or so) just haven't developed enough in their brains to be able to grasp those kinds of concepts.
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Zoom-boing
Platinum Member
JimBowie1958
Old Fogey
- Sep 25, 2011
- 63,590
- 16,890
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- Thread starter
- #34
Theory?
Have you ever been to a store?
Have you ever heard a cashier count change?[/quote]
Not in the last twenty years, no I haven't.
No, they don't. I had never heard it given that way.
Maybe where you are from, but not where I am from. They see the change indicated by the register and then count the change out to the same total. Haven't even seen that done in a long time. Now they just put the change, bills an receipt into your hand and say 'have a good day.'
Yes, I do.
Why not subtract 100 from 1001 instead?
OohPooPahDoo
Gold Member
Try handing someone $5 for a $4.76 purchase - and then handing them the penny AFTER they've already rung it up. It will blow their minds to pieces. Some just give up and hand you back two dimes and 5 pennies (emphasizing their stupidity).
Of course - most cashiers these day get paid shit and have no ownership interests - so what do you expect? 60 years ago the cashier was the owner or it was a faithful employee that took pride in his work and who the owner treated with dignity and respect - or maybe it was the son of the owner who would one day own it - now cashiers are disposable commodities going for minimum wage or slightly more if you want one that can figure out 5 pennies and two dimes is a quarter if you add it all up.
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OohPooPahDoo
Gold Member
JakeStarkey
Diamond Member
- Aug 10, 2009
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- #37
Thank you for proving my point.
'Count back 5 more to 20'---sounds like a roundabout way to use place value/10's.
No--I don't understand why they chose 15, etc.
I agree that Common Core is not only confusing...but does not fulfill it's stated objective...which is to instill A "core" of learned cognitive skills that all students can build on to enhance learning.
The way it's being implemented does not take into account a child's developmental ability to acquire specific cognitive skills at different stages of growth....
For example: Unless they are rare geniuses, children typically to not have the brain development necessary for abstract reasoning until @ age 12...So being forced to do algebraic equations and discern inferences and analogies at age 8 is invariably futile.
So.. In order to help kids pass the tests that measure stipulated "common core" acquisition, teachers are forced to instruct rote memorization of the kinds of answers required...which does not at all promote true learning unless the child is at the appropriate of stage of cognitive development.
Sent from my iPhone using USMessageBoard.com
The way it's being implemented does not take into account a child's developmental ability to acquire specific cognitive skills at different stages of growth....
For example: Unless they are rare geniuses, children typically to not have the brain development necessary for abstract reasoning until @ age 12...So being forced to do algebraic equations and discern inferences and analogies at age 8 is invariably futile.
So.. In order to help kids pass the tests that measure stipulated "common core" acquisition, teachers are forced to instruct rote memorization of the kinds of answers required...which does not at all promote true learning unless the child is at the appropriate of stage of cognitive development.
Sent from my iPhone using USMessageBoard.com
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FJO
Gold Member
I guess the people who unleashed the nightmare called "Common Core" never heard the expression: "If it ain't broke, don't fix it".
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