# Singapore math teaching left to right problem solving

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I have been using SM for years now homeschooling my children. I have found the left to right mental math and calculating such an essential part of SM. As essential as the bar modeling.It just makes so much sense to me. I wish I had been taught this as a child. Anyway recently I have been bumping into others that use SM and teach the usual borrowing and carrying over.

Anyone do the same?

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I haven't looked at those levels of SM, but it has to be the case that SM teaches both the mental math way and the traditional algorithm.  Does SM not specify where the addition is to be done mentally vs with the algorithm?

Edited by wapiti
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Singapore teaches the left to right technique first as it reinforces the concept of place value (and is much better for mental manipulation) and then moves on to what we think of as the standard algorithms for addition and subtraction.

I'm surprised that you haven't come upon this if you've been using Singapore for years as I think it is introduced in 2A.

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My understanding is they never show R-L addition or subtraction/borrowing or carrying in SM. It stays L-R throughout SM. That's one of the main reasons it is such a success.

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I should explain some more... I did the same as you ladies switching from L-R to R-L with my oldest around 3rd grade but you are not suppose to. My understanding is they never show R-L addition or subtraction/borrowing or carrying in SM. It stays L-R throughout SM. That's one of the main reasons it is such a success.

I knew at the time I should not have but out of convenience I switched my oldest. Im now working on going back to how SM is suppose to be taught L-R. I'm learning even with the larger problems it is so much faster for me and my children.

The only reason I took a look at how it was taught was because my oldest sometimes took so much time to solve problems or minor mistakes with carrying/ borrowing.

That's when I came across www.singaporemathlive.com and their 3rd grade mental math sample on there try it for free page.

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The Singapore Primary Math Series definitely teachers right to left addition and subtraction using the standard algorithm.

Here is a sample from Singapore 2 EP.

Wendy

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My understanding is they never show R-L addition or subtraction/borrowing or carrying in SM. It stays L-R throughout SM.

I don't have the right textbooks from SM to see the lessons, but I find it very hard to believe that the standard algorithm is not taught, especially in light of so many discussions on the vocabulary of composing/decomposing vs borrowing/carrying.  (Maybe that was a Liping Ma thing?)  Do any SM owners feel like checking?

ETA, thanks, Wendy :)

Edited by wapiti
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My understanding is they never show R-L addition or subtraction/borrowing or carrying in SM. It stays L-R throughout SM. That's one of the main reasons it is such a success.

No, it doesn't.  The textbook clearly teaches the standard algorithms for all four operations (starting in 2A).  I am not sure how you could be using Singapore math "for years" and not seen this (unless you've not yet gotten past 1B).

The reason Singapore math is a success goes well beyond how it teaches addition and subtraction.  The authors of Elementary Mathematics for Teachers, which uses the Primary Mathematics series to help teachers develop an understanding of elementary math at the level needed for teaching, do a great job explaining what makes the series great:

"The Primary Mathematics books give an extraordinarily clear presentation of what elementary mathematics is and how it is organized and developed.  They lay out the subject in depth, and they include a rich supply of exercises and word problems.  The mathematics is always clean and correct, and topics are repeatedly covered from different approaches.  Viewed from a broader perspective, these books provide much useful guidance about curriculum issues.  They exhibit the principles of a well-designed curriculum better, it seems, than any textbook series currently available in English."

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I stand corrected. You are right the singaporemath.com books teach this. Such a shame... It is so much faster and logical the other way. Identical to how you do mental math.

I question if this is the true Singapore way. My understanding it's not. Anyone know?

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I stand corrected. You are right the singaporemath.com books teach this. Such a shame... It is so much faster and logical the other way. Identical to how you do mental math.

I question if this is the true Singapore way. My understanding it's not. Anyone know?

The Primary Mathematics books first teach left to right addition/subtraction (and multiplication too, if I remember correctly).  *Then* they teach the standard algorithms.  Frankly, there are some situations when the left to right method is better and others where the standard algorithm is better.  It's good to know both.

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IMO, the program would be lacking if it didn't teach both.

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Interesting... I'll ask some SM gurus I know if they use the R-L at all.

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Interesting... I'll ask some SM gurus I know if they use the R-L at all.

It's right there in the Singapore math textbooks--the Singapore math textbooks *from Singapore*.

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The standard right to left algorithm is explicitly taught in the textbooks in both 2a and 3a, U.S. edition. But other mental techniques are taught, too.

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