Math 2.0 Subtraction-Decomposing -- HELP

[Anonymous]

Hi, I need to help my son and I do not understand decomposing. I know decomposition, but not this decomposing. Someone please help me! For example - the worksheet my son brought home:

For the problem:
698
-327

The sheet asks him to fill in the blanks:

_ _ _
-_ _ _
[u]
_ _+_ = _

I understand decomposition: 600 + 90 + 8 minus 300 + 20 + 7. I do NOT understand the problem the way the worksheet laid it out. with the two hundreds numbers going to a ten plus a one to equal a one digit?

[Anonymous]

Are there any worksheets that he has brought home previously that might give you any hints?

This is strange. Sorry.

[Anonymous]

But for the number of under scores you have, I would think step one is: 698-327=371. And the answer is 300+70+1=371.

[Anonymous]

If you tell methe grade, I can look up the answer for you.

[Anonymous]

Anonymous wrote:Hi, I need to help my son and I do not understand decomposing. I know decomposition, but not this decomposing. Someone please help me! For example - the worksheet my son brought home:

For the problem:
698
-327

The sheet asks him to fill in the blanks:

_ _ _
-_ _ _
[u]
_ _+_ = _

I understand decomposition: 600 + 90 + 8 minus 300 + 20 + 7. I do NOT understand the problem the way the worksheet laid it out. with the two hundreds numbers going to a ten plus a one to equal a one digit?

Are you possibly missing one blank? If so, decomposing is not about using a formula that a kid can just spit back without having any number sense. 698 is almost 700. 700 minus 300 is 400. 27 (left from the 300) minus 2 (the difference between 698 and 700) is 25. 400 plus 25 is 425. Your child can use reasoning and mental math to solve this way.

Yes, I am a teacher.

[Anonymous]

Oops, just realized I rushed and my math is wrong!!!

[Anonymous]

LOL, teacher!

That's OK, it's the process that counts, not getting the correct answer!

[Anonymous]

OP, I am also a teacher but have never heard of decomposing. I would send the teacher a note asking him or her to explain it or send more information on this process home. If you don't get a response, send the worksheet to the principal or curriculum supervisor and and THEM to explain it to you.

[Anonymous]

this is ridiculous. Can we just subtract the normal way?!?!?

I have 2 engineering degrees, work as an engineer, got great scores on the math SAT, got 5 on the AP calculus test and the normal way with borrowing, etc. has served me well.

[Anonymous]

Anonymous wrote:this is ridiculous. Can we just subtract the normal way?!?!?

I have 2 engineering degrees, work as an engineer, got great scores on the math SAT, got 5 on the AP calculus test and the normal way with borrowing, etc. has served me well.

Just because something works for you doesn't mean it works for all kids.

[Anonymous]

Anonymous wrote:this is ridiculous. Can we just subtract the normal way?!?!?

I have 2 engineering degrees, work as an engineer, got great scores on the math SAT, got 5 on the AP calculus test and the normal way with borrowing, etc. has served me well.

No, they don't do it the normal way anymore because lots of curriculum people are employed by thinking of new ways to do things in a more complicated way My son is in 2nd grade and his head is spinning with all of the zillion strategies for adding one digit numbers. Poor kid can't just say he knows what 4+5 equals. He has to use a strategy like doubles plus one or doubles minus one. He wrote "I just know it" on his test and he got that part of the question wrong. Seriously.

[Anonymous]

Anonymous wrote:this is ridiculous. Can we just subtract the normal way?!?!?

I have 2 engineering degrees, work as an engineer, got great scores on the math SAT, got 5 on the AP calculus test and the normal way with borrowing, etc. has served me well.

Absolutely!

What in the world are they thinking?

They are going to raise another generation of "touch point" math students who can't do elementary math to save their lives.

Math is math. This is nonsense.

[Anonymous]

Anonymous wrote:

Anonymous wrote:this is ridiculous. Can we just subtract the normal way?!?!?

I have 2 engineering degrees, work as an engineer, got great scores on the math SAT, got 5 on the AP calculus test and the normal way with borrowing, etc. has served me well.

Just because something works for you doesn't mean it works for all kids.

Most kids can learn basic math the traditional way.

For the one or two kids who can't, do a pull out and teach them in an unconventional way. Why loose 90% of the kids in order to maaaaybe (or not) reach a few of the others?

[Anonymous]

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:this is ridiculous. Can we just subtract the normal way?!?!?

I have 2 engineering degrees, work as an engineer, got great scores on the math SAT, got 5 on the AP calculus test and the normal way with borrowing, etc. has served me well.

Just because something works for you doesn't mean it works for all kids.

Most kids can learn basic math the traditional way.

For the one or two kids who can't, do a pull out and teach them in an unconventional way. Why loose 90% of the kids in order to maaaaybe (or not) reach a few of the others?

I am going to take a while guess here - you aren't a teacher are you?

[Anonymous]

Anonymous wrote:

Anonymous wrote: He wrote "I just know it" on his test and he got that part of the question wrong. Seriously.

Metacognition is actually really important, fyi.