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Public school math is confusing...

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 I watch my neighbor's daughter a couple days a week. She's in the same grade as my daughter, but goes to a private school which does the exact same curriculum as the public schools around us. I was having her do her homework when we got home since my daughter still wasn't finished with her school work. She finished realtively quickly so I checked her math over - not a single answer right.  It took me at least 20 minutes before I figured out what they were even doing before I realized she hadn't answered anything correctly! I asked her what they were doing in math and she had no clue.

It turns out they're working on mental math apparently and they're trying to have the kids write out what their brains should be doing.

          43 = ____ + 3
        +67 = _____+__
        ___ = _____+____+_____
That's an example of what they were doing, but there were no directions. So unless the kids knew what they were supposed to do, the parents were kinda out of luck with helping... But there was more to just that.....
What they wanted you to do on the next part was take it to the next level:

          43 + 67 
         +__   -__
          45 + ____= _____
I had a really hard time trying to explain this to her... I think they're still working on it for the rest of this week. The worst part is, they were working on multiplication just a few days ago and it seems like they're back tracking.

Any suggestions how I can help explain this to her?
I've tried showing her on the marker board and with blocks and then having her try using those.  She said she understood, but her face looked so confused.
My neighbor is constantly calling and asking what they're supposed to be doing in math since they never tell the parents what they're doing or what they're expecting

I meant to add this in before, but my daughter had finished up her math lesson while I was typing this earlier this morning and I forgot and just posted it...
The answer would be:

 43 = 40 + 3
+67 = 60 +7
___ = _____+____
But then you would solve the extended version first:
40 + 3
60 + 7

Then mentally you have to know that 10 can't be in the 1's column and 100 can't be in the ten and you'd put the correct answer in the correct spot of 110.
For the second part it would be:
 43 + 67
+ 2
45 + 65= 110

Sadly, it wasn't until I just typed this up when I realized they were trying to show mental math in 2 different ways...
Still, I have run out of ways to try and explain the concept to her.
Any suggestions??

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by on Oct. 10, 2012 at 11:33 AM
Replies (31-40):
by Silver Member on Oct. 11, 2012 at 8:41 AM

 Thank you :) That's essentially the same thing I told her last night and I think the bulb started to turn on in her head. She was able to do 2 correctly by hersef at least for writting it out, but the rest of it still had her lost. But we made progress!! LOL I'll take it :). I'm just really hoping now I can get her mom t come over and all of us work on it so that her mom can see what we're doing because Ithink we're getting somewhere.

Quoting KickButtMama:

When I had a PS'er staying with us, I taught this concept by saying you're breaking numbers up into place values. It helps if you say the words for each number, 439 is 400 and 30, 9. That's how we say it right? So write what you say, the numbers broken up. It's just breaking them up into their place values. Then it's less scary to add. How? Friends like to party together, right? So all the hundreds gets together for an addition party, and all the tens get together for an addition party and all the ones get together for an addition party. Then the result of the parties, tired, cranky numbers who've had too much sugar, have to get picked up by their families and mushed back to real numbers... So 439 + 78, 400 is too big, so it has a party by itself. 30 and 70 are the same place values so they party together, and 8 and 9 party together. When we add them, after a rockin party, we realize the 70 and 30 musta felt bad for the 400 partying alone because they decided to combine and make 100 so they could party with 400, the 8 and 9 have parties together making 17. So when we put things back together, we have 400 + 100 + 17, which is much easier to handle. All you have to change is the 4 to a 5. So the answer is 517...... Does that explain it better?

The point is, when moving from concrete math (maths dealing with specific values) and try transitioning to more advanced maths which deal with a lot more variables, it can be a huge leap. The New Math is a means of trying to make lower maths a little less concrete. It's just terrible at


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by on Oct. 11, 2012 at 8:42 AM
I have to say if my dd ends up doing this we are both shit out of luck....because I can't even figure that shit out.
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by Platinum Member on Oct. 11, 2012 at 8:43 AM

I don't know to explain that really well.

by on Oct. 11, 2012 at 12:11 PM

that is soooo confusing for kids .. my daughter did this one yr in public school and was thrown off that kids coudn't get the first part lol ... she would just solve problem and get bad grade because they wouldn't explain , but she knew what the math problem was lol ... good reason we don't do that anymore ;)

by Group Admin on Oct. 11, 2012 at 12:39 PM

 Do they always have to show 2 ways to do it?  Do they have to show it as breaking into tens and ones?  Can they break it into other "friendly" numbers?

My son understood it better when talking about subtraction.  My suggestion is to break out the base ten blocks and go over problem after problem.  :-(

by on Oct. 11, 2012 at 1:15 PM

Her mom could email the teacher for a kid-oriented approach.  This way they r teaching it the same way.

I know before doing mental math like that, my kids drilled extreme skip counting... not just by 2s 5s 10s... but starting at 2, skip count by 5s....

2, 7, 12, 17, etc..   then backwards til they could rattle off almost any skip count challenge.  This laid groundwork for their ability to visualize mental math patterns.

Quoting No_Difference:

 I was able to figure it out, but I don't know how to explain it at a level she can udnerstand it. Know what I mean? I've tried showing her with blocks, writing it with her on a marker board, and doing just random problems that were even easier than those on her worksheets... She's not grasping it at all and I'm running out of ideas.

Quoting KrissyKC:

The top one, I know, they are just breaking it down to tens plus ones... so they can learn to mentally add quickly.   My daughter (10) has been exposed to that in little bits over the years.

The second one, I started to say I had no clue, but I think what they are doing is mentally rounding the 43 to the nearest five (by adding two)... so you have to subtract two from the sixty seven.... to get 65... this way you can mentally add 45+65 = 110 easier than you can mentally add 43 + 67 = 110.

I, personally would have rounded to the nearest ten instead of five...   So I would have added 7 and subtracted 7, to get 40+60 to get 110 MUUUCH easier.


by on Oct. 11, 2012 at 1:19 PM

the plus side is, its just a brief section in most curriculum, and if the kid just cant do it... its not like the old fashioned approach doesnt work.

We also learned casting out nines... any one ever heard of that???   i had to google it for a few days because i didnt get what rod and staff was teaching.

by on Oct. 11, 2012 at 2:46 PM

Public schools need to teach Math that is actually used day to day, not crap 98 % of the population DOES NOT use. 

by Member on Oct. 13, 2012 at 2:34 AM

Actually that is sort of the way I already do math. I add the ones first, then the tens, then the hundreds and so on, then I add all that up. The difference is that I don't think 43 = 40+3 and 67=60+7. I just think 7+3+10, I usually carry the one but sometimes I won't. Then I have 4+6=10. I know that 10 10's equals 100 so 100+10 is 110.  It's much quicker when I do it in my head. 

I also sometimes do think sort of like the second way too. It's easier to add with 5's or 10's, so I might "borrow" 2 from the 7 to make it 45+65. Or I might "borrow" all 3 and add them to the 7 to make another 10, then I have 40+60+10 which again is easier. My DS counts up in his head. 67, 68, 69, 70. 70, 80, 90, 100, 110. I hope when he has to take the state test sometime this year, he won't have to show his work and can just give them the answer.

by on Oct. 13, 2012 at 2:37 AM
1 mom liked this

I'll stick with my blocks and MUS, lol. 

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