Place Value and adding 9's

[Lovedtodeath]

DD kept adding 8 and 9 and telling me the answer was 17, but writing it as 71. So I went off on a tangent reviewing place value with her and she liked to have never understood it. She was very frustrated and she could erase 71 and write 17 but could not tell me why it was wrong. So... do I need to review place value, or is this normal and not a manifestation of a lack of understanding? If it is a lack of understanding will reviewing the same thing do any good, or should we move forward to 2 digit adding and hope that this cements it?? TIA

[Amber in AUS]

Do you think she is just reversing it when writing it down and she thinks she has written 17 until you show her? Was is just 17 or other numbers too?

 

Maybe do some verbal stuff, use magnets or number cards for her to show you the answers. I would change it up a bit to try to find out if it is understanding she is lacking or if developmentally she is having a hard time working it all out, then getting it down KWIM.

[Wee Pip]

I've discovered that when you teach your child something new, all previous knowledge goes completely out the window:D I just state the obvious but keep moving ahead. In other words, I don't back up a lesson, I keep plugging ahead. I go slow, I break our lesson in half for each day, and I just explain the old easy stuff right along with the hard stuff. When I taught my girls how to add tens and ones (ex: 41 + 34), my girls completely forgot how to add 1 to a number. I suddenly found myself explaining how to ADD ("what's one more than 4? Count up one. No, let's try again. What's the number after 4? Here's a numberline, go up to the number after 4. 5, the answer is 5!" LOL). I'm not kidding, it was that basic! But after explaining each problem step by step, and reteaching basic adding at the same time, my dd caught on within 2 weeks and was able to do it on her own. Now, if I noticed after 2 weeks that the old and new was still foggy, then maybe I'd back up. But so far, reviewing while moving forward has done the trick.

[KathyBC]

I agree with Wee Pip - review the old stuff while you keep moving on for a couple of weeks and see if that solves the problem.

 

Something that comes to mind in your particular example is that one hears the "seven" first when you say seventeen. The English language is notoriously bad for confusing place value between 11 and 19. Does she do this with numbers beyond the teens? When my kids have had this same difficulty, I try to follow what Steve Demme of MUS says and sometimes address the teens as 'onety' (for one ten, just like seventy is seven tens);I might say 'onety-seven' a couple of times, as well as the conventional 'seventeen', so they can hear which number to write down first.

 

HTH.

[StephanieF]

Same issue here! I have to keep reviewing it-daily if I can. I just remind ds "how many tens in seventeen, are there 7?" Teen means 10 and they just have to get used to the seven being said before the teen.

That is why I don't just do addition orally but make him write it down

Stephanie

[Alana in Canada]

For what it's worth--my kids never add 9--they add 10 and subtract one.

[Chris in VA]

She might need a review of place value, but her problem could also be as simple as this--

When you write 17, not in a problem but just outright, you write the one then the seven. When you write seventeen in a math problem, you write the seven first (in the ones place) THEN the one (in the tens place), so it feels "backwards" to the mind and the hand. Does that make sense?

[Lovedtodeath]

I agree with Wee Pip - review the old stuff while you keep moving on for a couple of weeks and see if that solves the problem.

 

Something that comes to mind in your particular example is that one hears the "seven" first when you say seventeen. The English language is notoriously bad for confusing place value between 11 and 19. Does she do this with numbers beyond the teens? When my kids have had this same difficulty, I try to follow what Steve Demme of MUS says and sometimes address the teens as 'onety' (for one ten, just like seventy is seven tens);I might say 'onety-seven' a couple of times, as well as the conventional 'seventeen', so they can hear which number to write down first.

 

HTH.

 

We have MUS and I did... she didn't get it and couldn't build any two digit #s correctly on decimal street either.

 

For what it's worth--my kids never add 9--they add 10 and subtract one.

That is how we do it too.

 

She might need a review of place value, but her problem could also be as simple as this--

When you write 17, not in a problem but just outright, you write the one then the seven. When you write seventeen in a math problem, you write the seven first (in the ones place) THEN the one (in the tens place), so it feels "backwards" to the mind and the hand. Does that make sense?

Yeah, learning to write the ones first is a problem that MUS has not addressed yet. I wish they had taught it that way when we learned place value.

[Lovedtodeath]

Do you think she is just reversing it when writing it down and she thinks she has written 17 until you show her? Was is just 17 or other numbers too?

 

Maybe do some verbal stuff, use magnets or number cards for her to show you the answers. I would change it up a bit to try to find out if it is understanding she is lacking or if developmentally she is having a hard time working it all out, then getting it down KWIM.

 

I've discovered that when you teach your child something new, all previous knowledge goes completely out the window:D I just state the obvious but keep moving ahead. In other words, I don't back up a lesson, I keep plugging ahead. I go slow, I break our lesson in half for each day, and I just explain the old easy stuff right along with the hard stuff. When I taught my girls how to add tens and ones (ex: 41 + 34), my girls completely forgot how to add 1 to a number. I suddenly found myself explaining how to ADD ("what's one more than 4? Count up one. No, let's try again. What's the number after 4? Here's a numberline, go up to the number after 4. 5, the answer is 5!" LOL). I'm not kidding, it was that basic! But after explaining each problem step by step, and reteaching basic adding at the same time, my dd caught on within 2 weeks and was able to do it on her own. Now, if I noticed after 2 weeks that the old and new was still foggy, then maybe I'd back up. But so far, reviewing while moving forward has done the trick.

 

Thanks for your support and reassurance!:grouphug: That goes for everyone! Is anyone else afraid of leaving someone out in a response?:D