Why 5+5+5 doesn’t always make 15: Maths exam question divides the internet

[hawk007]

A Year 3 pupil was marked down for the solution written out for 5x3

Working out the answer to 5x3 may seem simple enough but the solution one student gave has sparked an online debate.

The maths question, which asks pupils to work out 5x3 using the repeated addition strategy, was posted on Reddit.

It shows a Year 3 pupil being marked down for the solution 5+5+5, with the teacher noting the correct working out should be shown as 3+3+3+3+3.

A second question asks students to draw an array to show and solve 4x6, with the student drawing six rows of four as the answer. This is also marked as incorrect, with the teacher highlighting four rows of six as how it should be written out.

The National Council of Teachers of Mathematics (NCTM) in the US defended how the paper was marked, saying it gives students a better understanding of the problems they are solving.

"Part of what we are trying to teach children is to become problem solvers and thinkers," said Diane Briars, president of the NCTM.

"We want students to understand what they're doing, not just get the right answer."

The Common Core State Standards for English and Maths has been widely adopted in the US and outlines what each student should know in each subject by the end of each grade.

Critics claim the different approach can be too confusing for children, while supporters believe the methodology pays dividends when students move on to tackle more difficult problems.

"I would totally argue with the teacher over that for my child," commented one user.

However another replied: "This is a mark of a good teacher. If your question doesn't achieve the desired result then the question was the problem, not the answer."

SOURCE

[jamesDDI]

:lol:

well the teacher has right btw ^_^

[Nastrahl]

This is completely retarded.

It's neither easier or harder since there are just X identical paths for the same answer and which one you take doesn't matter since it's not specified in the question.

[hawk007]

Teacher was right. The Question was to give the answer of 5x3 using the repeated addition strategy.

Since Multiplication is nothing but the successive addition, that is, 5 times 3; equal to 3+3+3+3+3 = 15.

But, 5+5+5 = 15 is not correct. (if notation was 3x5, then it was correct)

[jamesDDI]

Teacher was right. The Question was to give the answer of 5x3 using the repeated addition strategy.

Since Multiplication is nothing but the successive addition, that is, 5 times 3; equal to 3+3+3+3+3 = 15.

But, 5+5+5 = 15 is not correct. (if notation was 3x5, then it was correct)

Perfect ^_^

[info999]

good thing I was born in the 80's, maths was WAY easier back then :rolleyes:

[CODYQX4]

Ah I though it was bad enough having to do some long and drawn out problem in college, and getting docked 3X harder for missing one step, than actually getting a similar question wrong.

Gotta split hairs then lord authority over them to teach them to be good peasants.

Who the f*** actually does their math on paper like that. I understood that it was addition over and over, without having to write it a specific way or getting docked.

There's too much focus on "do it this way because I said so, I don't care if you're right and understand it", and not enough actual teaching.

So 3+3+3+3+3 is right but 5+5+5 is wrong? Because it's written 5x3? I think it makes more sense given we read left to right.

Also, 5x3 is 3x5 so that's a stupid point. It doesn't matter in what order the two numbers being multiplied are.

It looks like the student understood, but also logically read 5x3 = 5+5+5 because with no order of operations, it makes sense to read left to right. But teacher is all like "OK smartass you're wrong. Read that shit right to left even though it both the same logic and same final answer. STFU and take your -1 and go flip burgers".

I always found this the most infuriating bull, because some teachers actually dock more for this kind of nitpicking than they do following their order and getting the wrong answer.

[CODYQX4]

Oh and on that Common Core, let's bring out those tests that subtly hint that the President is all 3 branches of government.

We make our own hell, this deranged society we live in, and the most insane inmates are running the asylum.

[dMog]

the issue here is showing understanding of how to solve the question as asked...not solve the question any way that works... it would have been better for the teacher to give some credit for getting the correct result but explain that sometimes a specific and exact way to solve was required in this case... it goes a long way to teach that understanding an exact way to solve was asked here ..plain to see the kid was smart enough to know the answers and i really do not think the kid will will be scared for life over this...unless the parents choose to insist on it

[hawk007]

"We want students to understand what they're doing, not just get the right answer."

Not to overlook this philosophy. Else, the purpose of education will fail in the long run.

[dMog]

an entire generation has been brought up to think they can do no wrong so good to see proof that they will be bringing up their kids in the same manner.... nice to see though that the parents did not demand the teachers head on a platter for this egregious attack on their child

[CODYQX4]

Do it this way because it "might" help at the highest levels of math we'll teach you, that you'll most likely never use, but let's hand-wring and teach the most basic fundamentals. I did matrices and I'm a developer and I've never had to bust out Calc to do any of it, but yeah let's totally change the way we teach basic math because it might insignificantly help someone learn that.

Meanwhile, if we fail, we'll have taught people how to do basic math with 4x the steps for no gain whatsoever when that time could have been used better elsewhere.

[flitox]

so let me resume the thing from what i'm understanding, the correct answer is 3+3+3+3+3 because you say in english 5 times 3, right???

problem is that in my langage, you say 5 multiplied by 3, which definitively is 5+5+5.

so let's be an ass and say that teacher is as wrong as pupil because he didn't ask the good question which should be: use the repeated addition to solve...give all possible answers.

[jamesDDI]

It's correct and it's the better way, there is few to do imo.

5x3, is better to read like 5 times 3 like when we have 5X we read 5 times the values of X. This is the more correct way and the child will be advantaged with more complex math in his future. ;)

[hawk007]

problem is that in my langage, you say 5 multiplied by 3, which definitively is 5+5+5.

so let's be an ass and say that teacher is as wrong as pupil because he didn't ask the good question which should be: use the repeated addition to solve...give all possible answers.

Arithmetic operations are: Addition, Subtraction, Multiplication & Division.

The latter two evolved from the former two.

Multiplication = Repeated addition

Division = Repeated subtraction

So, I never talked in your language or mean that. This is based on arithmetic operations and the teachers wanted the pupil grasp the fact.

[jbleck]

english vs. math... and the winner is... english cause math is too vague :P

[Edgar.Elooo]

The order of the factors does not alter the product.

Commutative property of multiplication.

[wallofasgard]

I think the student was wronged not because of the answer but the student followed the wrong instruction.

"He should go right but instead he takes left".

[dMog]

my math teachers used to grade problem like this id a way different way... getting the 1 part of the mark for each problem as follows following the instructions properly...ie solving the problem in the way you were asked to...as he put it there are several ways to solve problems...i asked you to do it in specific way... so solve it that way... or you will lose points when i mark another point for showing your work and another point for getting the correct answer///so this kid would have got two out of three and then got to understand in math as in life you you have follow directions better to be successful :) ...why is it so hard to understand this life lesson for 90% of the people saying the teacher was wrong...a specific and exact way was asked ...even though there are several ways to get the correct result....it shows that the student understands the differences... and heres the catch detractors...making mistakes and learning form them is also educational because you learn from that too.... we need to stop teaching our kids that they can do no wrong especially when they do do wrong... and lets open thar can of worms of not keeping score in sports or recognizee the fact that some kids are just naturally athletic and excel in sports better than others..is it right hold them back because some other kids will feel bad because they did not win the race...some schools no longer give awards for academic and sports achievements because it will hurt the feelings of some other kids...

[jbleck]

my math teachers used to grade problem like this id a way different way... getting the 1 part of the mark for each problem as follows following the instructions properly...ie solving the problem in the way you were asked to...as he put it there are several ways to solve problems...i asked you to do it in specific way... so solve it that way... or you will lose points when i mark another point for showing your work and another point for getting the correct answer///so this kid would have got two out of three and then got to understand in math as in life you you have follow directions better to be successful :) ...why is it so hard to understand this life lesson for 90% of the people saying the teacher was wrong...a specific and exact way was asked ...even though there are several ways to get the correct result....it shows that the student understands the differences... and heres the catch detractors...making mistakes and learning form them is also educational because you learn from that too.... we need to stop teaching our kids that they can do no wrong especially when they do do wrong... and lets open thar can of worms of not keeping score in sports or recognizee the fact that some kids are just naturally athletic and excel in sports better than others..is it right hold them back because some other kids will feel bad because they did not win the race...some schools no longer give awards for academic and sports achievements because it will hurt the feelings of some other kids...

yep... i don't think Uncle Sam is a fan of this or ever will be.

there's only Uncle Sam's way and the other ways will be destroyed... funny how they teach these things :P

[dMog]

my math teachers used to grade problem like this id a way different way... getting the 1 part of the mark for each problem as follows following the instructions properly...ie solving the problem in the way you were asked to...as he put it there are several ways to solve problems...i asked you to do it in specific way... so solve it that way... or you will lose points when i mark another point for showing your work and another point for getting the correct answer///so this kid would have got two out of three and then got to understand in math as in life you you have follow directions better to be successful :) ...why is it so hard to understand this life lesson for 90% of the people saying the teacher was wrong...a specific and exact way was asked ...even though there are several ways to get the correct result....it shows that the student understands the differences... and heres the catch detractors...making mistakes and learning form them is also educational because you learn from that too.... we need to stop teaching our kids that they can do no wrong especially when they do do wrong... and lets open thar can of worms of not keeping score in sports or recognizee the fact that some kids are just naturally athletic and excel in sports better than others..is it right hold them back because some other kids will feel bad because they did not win the race...some schools no longer give awards for academic and sports achievements because it will hurt the feelings of some other kids...

yep... i don't think Uncle Sam is a fan of this or ever will be.

there's only Uncle Sam's way and the other ways will be destroyed... funny how they teach these things :P

i think you are misconstruing the problem here..this has nothing to do qith uncle you know who...it is a commentary on society in general and not just the usa

[pc71520]

Math? Not my subject...

[dMog]

Math? Not my subject...

math still hurts my head

[pc71520]

Math? Not my subject...

math still hurts my head...

My heart, too. :lol:

[CODYQX4]

so let me resume the thing from what i'm understanding, the correct answer is 3+3+3+3+3 because you say in english 5 times 3, right???

problem is that in my langage, you say 5 multiplied by 3, which definitively is 5+5+5.

so let's be an ass and say that teacher is as wrong as pupil because he didn't ask the good question which should be: use the repeated addition to solve...give all possible answers.

I speak English and reading 5x3 just logically looks like 5+5+5 because we read left to right.

It's then completely irrelevant because multiplication is the same no matter the order.

I hated the way math started to be taught. It wasn't about the logic it was "this is an X type of problem, do it this way and don't you dare ask why".

I mean we're arguing about order. I don't think I dealt with matrices that they claim nitpicking over, until late High School, and they're teaching multiplication earlier in some places. Learning pre-Common Core didn't trip me up.

Also, people will disagree but a lot of teachers just love being right and will tear your stuff up if you have the audacity to ask why, you know because you want to actually understand. Hell I've been docked in college for not showing a very simple step on a problem that wouldn't quite fit in the space they gave, more docking than getting it wrong, just because. If I cribbed the answer I wouldn't have a dozen steps down and omit the easiest one, but that's the BS excuse, that if you write down less steps than they expect you're probably cheating. We're talking calc and skipping a simple multiplication of 2 numbers within a pile of hard shit.

That's a pretty awful way to teach math, when it's just endless rules/memorization and they gloss over the logic. They started this halfway while I was in school, and it made it much harder to reapply older concepts, because they never focused on understanding "why", just this is that type of problem so grind through this way. Even in college. No wonder everybody hates it.