Why '5+5+5=15' is wrong under the Common Core

Business Insider ^ | October 25, 2015 | Jacob Shamsian

[grundle]

Here's a "repeated addition" Common Core problem that's taught in third grade in US schools:

Use the repeated-addition strategy to solve: 5x3

If you answer the question with "5+5+5=15,” you would be wrong.

The correct answer is "3+3+3+3+3.”

Mathematically, both are correct. But under Common Core, you're supposed to read "5x3" as "five groups of three." So "three groups of five" is wrong.

According to Common Core defenders, this method will be useful when students do more advanced math. This way of reading things, for instance, can be used when students learn matrices in multivariable calculus in high school.

But parents aren't happy about it.

[FoxInSocks]

Have you seen kids try to figure out the change you should get back?

Picture this. The total due is $7.35. I'll hand over $13.00. The clerk will tell me it's only 7.35 and take the ten. I pocket a fistful of ones.

[Norm Lenhart]

Like hell they are. They are SUCCEEDING. There is no try. And they are REALLY good at it.

[bakeneko]

Everybody knows that mulitiplication tables are racist.

Get out of here with your white-centric math and stuff.

[Norm Lenhart]

I know what it is. It’s something people mentally unfit for creative writing at a high level do to keep their little pea brains occupied...

(Said the guy that failed algebra ;)

[MarchonDC09122009]

RE: “it’s the wrong answer”.

Big Brother: “Winston Smith, tell me how many fingers I’m showing now!”

Winston Smith: “three, four, or two, it’s anything you say they are - anything. Please, I beg you, stop torturing me!”

George Orwell’s 1984 (a socialist’s guide for governing)

[E. Pluribus Unum]

The nuns taught us our multiplication tables in first grade and how to add, subtract, multiply, divide and take square roots by third grade.

Everything the feral government touches it destroys.

[CodeToad]

“I teach 4th grade Math. This year at our Open House night, I had to prove to several parents that we don’t use Common Core lessons or curriculum.”

Fantastic! Good for you and your school system for not using the Ebonics of education, and good for the parents demanding that you don’t.

[ronnietherocket3]

Calculus for the following y=f(x) is generally referred to a single variable calculus. There is even an MIT open courseware course called

[WildHighlander57]

Wreck the system.

Say 5+5+5.

Never give up.

If the common core edu-robots fail everyone based on common cores warped ideas , then common core will collapse.

Wreck the system.

[MarchonDC09122009]

BINGO!
That’s what I told our kid’s idiot third grade teacher, when she was teaching bullsh1t Mimosa “new” math in the mid-nineties.
Fixed that cap with homemade multiplication flash cards in one night. The kid memorized the tables up to 12 x 12.
His fifth grade scout friends semi-boasted that they still had to use their fingers or hash marks on paper.

Our kid became a successful EE.
His fifth grade slacker friends went into government studies..

The adle-brained educational system, and crappy parented kids guarantees our continued downfall.

RE: “5 X 3 = 15 and should not need to be factored out if they were still memorizing their tables.”

[Harmless Teddy Bear]

Some can’t do that so it’s only fair that none can do that.

You have it the wrong way around.

It is actually easy to memorize the table and everyone can do it. That is why they do not do it. The goal is not to educate but to prevent education by making everything very confusing. That way only a very few will come out of public education with any sort of idea of what is going on.

These methods are not used in the private schools of the elite.

[ronnietherocket3]

Evidently, my post did not finish. It should have been: Calculus for the following y=f(x) is generally referred to a single variable calculus. There is even an MIT open courseware course called Single Variable Calculus.

[WildHighlander57]

Do it anyway.

After hours extra credit :D

[grania]

This is dumb. For one who counts out 5 x 3 quickly on their fingers ("skip counting"), they'll use 5, the first number, and count on three fingers 5,10,15. If they switch it. they're more likely to make a mistake.

For students who are average or struggle a bit with math, quickly counting out the numbers, using the sense of touch, helps them learn their times tables faster.

Common Core is insane.

[grania]

re: Common Core. Piaget must be rolling over in his grave

[Nifster]

actually it’s a rule....as in commutative

[Nifster]

true that

[Leaning Right]

Do it anyway. After hours extra credit :D

I like the way you think. Because it certainly can't be done (legally) in the classroom.

Here's an example. Our physics curriculum handbook (actually it's a big binder), sets out in detail what I must teach every day. No variations permitted! There are no lessons on torque. So I must not teach it! But torque is a key concept in physics.

So I sneak it in wherever I can. Fortunately, most supervisors who observe me know nothing about physics. So I haven't been accused (yet) of "infidelity to the curriculum".

Yes, that's the term they actually use. And it's a firing offense. Crazy.

[P.O.E.]

Zero is my hero.

[MichaelCorleone]

I know for a fact several Elementary school teachers tell their students up from that their parents will be shocked at what is being taught and just won’t understand it. They do things the ‘old way’, but *we* do math the new and improved way.

Message being your parents are old school; old fogies who just aren’t ‘with it. Disregard your parents’ ignorance and learn it our way.

Enough of them do it where it’s got to come from a central source. Whether it’s the official CC line, I don’t know.