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We just started adding vertically in Singapore 2A. I'm trying to get ds to add from right to left, but he insists that it's easier to go from left to right. He's dyslexic, so he is very used to me telling him read everything from left to right. He used to write and read from the wrong side of the page, now I want him to go right to left, he's fighting me.

I've tried to stump him with adding numbers that carry over, but he got it right away. Singapore doesn't explicitly teach this concept of starting with the ones column, or maybe it does, and I missed it. He's the type of kids that will sit in the car and say, " Mom, do you know what 584 plus 263 is?" And then he will tell me the answer. I'm still trying to remember all the numbers he just told me. I'm not a mathy type, and like to see it on paper all lined up in neat columns, so I can add it. DS told me he just looks at the whole number and then adds it. Should I insist that he start from right to left, or just let him go until he realizes that it's too difficult to do it that way.


Thanks,
Tracy

I haven't used Singapore in a while, but I seem to remember in 2A that the stress is always on mental math, mentally rearranging larger numbers so they are easier to work with. For example 23 + 19 could be thought of as 22 + 20, or 20 + 10 + 3 + 9, both of which would be easy to add up mentally to 42, without doing the right to left columns and carrying. I think Singapore introduces the vertical method later on-but hopefully someone who is now using Singapore can verify or correct my answer to you Sounds like your ds is doing well with mental math, and I wouldn't discourage that, anyhow

As a dyslexic my advice is to require him (in his school work) to do it in columns from ones to tens to hundreds etc... Unless of course its mental math then he's ok as hes seeing the numbers and grouping them together. Are they asking him to do it mentally. I'd be fine with 154 + 264 and him coming up with 418 by adding in the hundreds first.. but not ok with him adding 123 + 234+ 456+ 567, the same way, that should be placed in a column and added.

I know what he is doing, and it will work for a while, but as the math gets more difficult and he has more pieces to add and more to hold in his short term memory it WILL fall apart. Not to mention he will easily do 3 times the math with all the back tracking you need to do with carrying etc.

So if the work book has them in neat orderly rows and columns, I'd just get out the handy dandy 3X5 card and cover up those other numbers in the tens and hundreds column, and tell him for now he has to get in the habit of adding units first then tens then hundreds. Because that habit will help him in the long run. When I hit algebra my odd handling of numbers/math caused math to crash down around me, I had to back track and learn this skill/habit. And if they are written horizontally in the work book then they are meant to be done mentally and as long as the right answer is coming up its ok. He shouldn't have to rewrite the work book.

Tidbit... I still subtract 8 from 16 by thinking 16 divided by 8 = 2 so since there are 2 8's in 16 the answer is 8... See what I mean... way more work then just taking 8 from 16, but I hated carrying I'll do division to avoid carrying.

EDIT: dyslexia strikes again! I edited my post to make it more clear.

I was taught starting at the right and moving left, borrowing/carrying etc.

I actually do mental math left to right. I was never taught that, but figured it out.

In 3B they actually start out by working on adding by going left to right.

MomtoJGJE, did I understand you correctly. In 3B they start adding by going from left to right, or did you mean right to left? I never really understood what every one was talking about when they would say, "mental math", but now I think I understand. DS has been doing mental math all along. Tansy, I loved the idea of using the 3x5 card, so we used it the very next day. So, now I'm still confused. Should he be doing mental math right now, and then as he gets into the upper guides, start making him add, subtract in columns?

Thanks,
Tracy

left to right, as in add 10s first and then ones.

Like... if they had 34 + 59... they'd say 30 +50=80, 9+4=13, 80 +13=93

They also do that problem with regrouping so they'd do like 59 would be 53 and 6, so you'd then have 40 and 53, which is 93.

I would say as long as he's able to talk through the problem, not to worry about it. I think it was in 3A that Jayden was adding and carrying right to left. So they do cover it.

Oh my sorry for my dyslexic post Sigh 45 an I still get my rights and lefts mixed up... I corrected it for clarity.

So If the work book is horizontally written 342+621= then its ok with me if he adds them in his head any way he wants to, because Singapore encourages mental math.

but if its written on his sheet this way...
342
+621
Then I'd use the handy dandy 3x5 card to train his mind...

If he balks then show him an impossible to add "mentally" number like United states annual budget Plus the annual budget of say India...
3,972,854,361,765.01 (I made some of these numbers up)
+1,457,875,542,310.04
calmly add them together using the columns.
Bingo that was so easy...

Tansy, LOL, yes that would be more difficult to add in your head. LOL. Ok, so I'll just let him do what he's doing and let it be for now. He seems to be getting the mental math even if I don't...LOL.


Thanks MomtoJGJE and Tansy.

Aren't our dyslexics just the BOMB! hehe... Anyway, if he can add it mentally (in his head) and he gets it right, I wouldn't care how he did it. My dyslexic boy was coming up with better strategies than Singapore a long time ago. If he needs to work it out on paper, I would require him to move from right to left. Keep stressing the names of the place values. "We have to start with the ones and go to the tens, etc." The index card is a great idea. If he is having trouble keeping the numbers lined up, use graph paper.

hth,
Laura