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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...

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

100+10
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??

by on Oct. 10, 2012 at 11:33 AM
Replies (11-20):
by on Oct. 10, 2012 at 5:54 PM

43 = ____ + 3
+67 = _____+__
___ = _____+____+_____

Actually I think I do understand this:

43=40+3

67=60+7

110=100+7+3

I don't think I understand the next part. I'll try tho.

by on Oct. 10, 2012 at 5:56 PM

43 + 67
+__   -__
45 + ____= _____

43+67

+______-_______  <------- No freaking clue at all....

45+65=110   <-------Maybe that is what they are wanting there?

by on Oct. 10, 2012 at 6:14 PM

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. 10, 2012 at 6:15 PM

As a side note, my daughter is getting primed to move onto algebra next, so I've had some more experience with this level of mental math.   Prior to that, I would have had no clue.

by Silver Member on Oct. 10, 2012 at 6:38 PM

It's partially rounding and it's trying to get the kids to understand how their brains break down a math problem so they can do it mentally... At least that's what I'm gathering because it keeps saying, use mental math...but it wants you to put out all the answers...

So it's
43= 40+3
+67=60+7

and then you solve it backwards...3+7= 10, 40+60=100.  10 can't be in the 1's place and 100 can't be in the 10's so you carry everything and you get 110.
That was ONE of the ways they had to solve it.

The other way was to subtract 2 from 67 and add it to 43 so you're new problem would be 45+65 and then do all that crazy stuff above.

It took me awhile to understand what they were showing, but I don't know how to explain so she understands it.  I also have NO clue how  a parent that doesn't know what they're doing is supposed to know how to help them unless they're sitting down and spending a ton of time trying to figure out themselves too.

I know she doesn't understand what she's doing because she couldn't answer the critical thinking question at the bottom of the page, Why is it easier to add some numbers than it is others?  It took me another 20 minutes of showing her more problems and talking her through the answer before she finally understood the answer.

Quoting calimom1123:

This is exactly what I was thinking. Bju learns similar to this. The other part im not sure because we do it this way..

43+67

67+3=70

You round 1 number to the closest tens then subtract the same amount it took to get there. Does that make sense?? Not sure how they got 45 though.

Quoting soy_latte:

Is it suppose to be getting them to add large numbers by rounding?

43 = 40 + 3

67 = 60 + 7

43 + 67 = 40 + 60 + 7 + 3

by Silver Member on Oct. 10, 2012 at 6:40 PM

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. 10, 2012 at 6:43 PM
My son brought that home last week and I looked at it and thought, what the hell is this? Asked son what he had to do and he gave the same answer she did, "no idea mom." Needless to say, my brother helped ds and I with homework that night. He is a teacher.
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by Silver Member on Oct. 10, 2012 at 6:44 PM

RIGHT?! That's what I was thinking. I was happy I was able to figure it out yesterday, it's just explaining it so it makes sense to an 8 yr old is what seems impossible!

Quoting kirbymom:

Holy mamma! What kind of math is this?! I have never learned this and couldn't even begin to try and help explain it. This new fangled way of doing math would make me look like I was dumber than a bag of bricks. Even though I am not that bad. :)   I am sorry for not being able to help you. :(

by Silver Member on Oct. 10, 2012 at 6:47 PM

Yes she's in the public/private school out here.They all use the same curriculum...not sure what math program they're using specifically though. They don't have a book to bring home, just worksheets, and no explainations for the parents (or babysitters in my case).

I did have her do easier problems with me, but she's still struggling. I think I finally made some progress though when I had her say the number outloud and write it at the same time so if she said 473 she was actually saying and writing 400 70 3 and was able to break the first part down. But trying to explain that this is how they want your brain to compute this is not making any sense to either of us lol

Quoting romacox:

That is the new math, which teaches math concepts. Even if the children get the right answer, the school system counts it wrong if they did not do the process as  wanted. College professors complain that public schooled kids are entering college not knowing how to do basic math. I think it is because of the new math.  It does not teach analytical thinking.

But it sounds like she is not homeschooled.  So you will need to teach her the "new math" used in public schools. I would break the problem down in smaller pieces, and take one step at a time using objects (such as pennies or blocks as you mentioned).  Also I would start out with smaller numbers, and work up to the larger numbers.  Make it as experiential as possible.

by Silver Member on Oct. 10, 2012 at 6:49 PM

can he explain the concept to me ?? LOL  What is the point behind it other than to confuse the parents/gaurdians?? LOL

Quoting cowboygal:

My son brought that home last week and I looked at it and thought, what the hell is this? Asked son what he had to do and he gave the same answer she did, "no idea mom." Needless to say, my brother helped ds and I with homework that night. He is a teacher.