This Might Explain a Lot About Conservatives

[walkitout]

http://www.businessinsider.com/common-core-subtraction-2014-10

Conservatives don't like Common Core. That's not news. Red State is a blog. Also not news. Red State's editor in chief Erickson says his wife and his 3rd grader can't understand subtraction. Specifically, the counting up method of subtraction, an alternative method of subtracting that anyone who does mental arithmetic does automatically, and which is included in Common Core textbooks and has some nice side effects like helping people internalize quantity and quantitative relationships, rather than just relying blindly on a sequence of nonsensical steps the way traditional algorithmic arithmetic tends to encourage people to do.

"Erick Erickson wrote that this method "makes no freaking sense to either my third grader or my wife.""

If conservatives in general are innumerate, it might or might not be news, but it would be a very powerful explanation for some of their positions (not their terrible morals, but why they keep getting suckered by foolishness about the effects of tax cuts).

I had never seen (to the best of my recollection) this sequence of steps before, but it captures a lot of the rounding up/rounding down and then adding back in that I do mentally doing arithmetic -- I can't make the standard method work consistently without something to write on, but this one I can hold in my head. It took me a minute to understand the sequence they laid out, because it is a little different from what I do, but the spirit is recognizable. Anyone who has a lot of trouble figuring out this way of subtracting probably hasn't really understood subtraction, other than as a rote sequence of steps.

FWIW, I expect that anyone who _does_ have trouble with this might find that after a half dozen to fifty worksheets with a hundred of these problems on them will help them with their difficulties. It might even help them better understand quantity relationships as well, contributing to their overall numeracy.

ETA: the sequence in my head goes like this. 325 - 38 = ?

320 - 40 = 280
280 + 5 = 285
285 + 2 = 287

So I drop the trailing digits initially, rounding down on the larger number and up on the lower number, so I only have to add when I put them back in. Then I subtract the now manageable single digit from double digit (32 - 4 = 28) and put the zero back on. Then I add back the dropped digits.

Comments

[rolandgo.livejournal.com]

Mine goes:

325 - 38 is
325 - (25 + 13) is
300 - 13 is
287

That is on this one I get the larger number to something even first.

I would never have thought to do it that way

[walkitout]

Except actually, I sometimes do do it that way! Usually I do the rounding thing, so that I get close and can abandon with the close result if that is enough.

But I do reduce both numbers by the same amount sometimes. Thus:

325 - 38 =

(325 - 25) - (38 - 25) =

300 - 13 =

287

I would never represent it the way you did, but they are algebraically equivalent.

[jinasphinx.livejournal.com]

The common core math I have seen so far reminds me a lot of books of advanced math "tricks" that apparently people who are good at math do in their heads normally. Also, the common core long division I have seen makes more sense to me than the "regular" long division I had to learn as a kid.

The main argument I have seen against common core is that the parents don't know it, therefore they will not be able to help their kids with math. This seems like an argument that would work against any form of innovation. (Parents don't understand internal combustion! Therefore no horseless carriage education!)

"advanced" math

[walkitout]

One of the things I was trying to get at is that some people who are good at the "standard" algorithmic approach on paper are terrible at the "advanced" "mental" math -- and vice versa. Which calls into question what's really going on here. Over time, I learned and use both. My difficulties learning the "advanced" mental stuff was the oral presentation. Many kids have difficulties with the standard approach because the presentation is paper and pencil -- some of these kids can do the mental math "advanced" stuff super fast while I'm working through the standard version on paper.

I totes agree with you about the primary conservative argument, and will raise you a response! Relying upon parents to help the kids learn handicaps children who come from less well-educated families, children whose parents work long hours, etc. Public education was supposed to bring these kids up to some sort of standard. I like educational approaches that do not rely upon homework.

Re: "advanced" math

[ethelmay.livejournal.com]

I typed almost the exact same comment as Roland's and then deleted it.

I've met several kids with dyslexia and/or dysgraphia who have an awful time dealing with written numbers. The kid with dysgraphia (or rather the kid whom I'm pretty sure had dysgraphia) was just painful to watch. No one had ever told her about using big graph paper (or turning lined paper sideways and using the lines for column marks), and she routinely got anything more than two columns wide misaligned, and sometimes anything more than one. It's not surprising mental math would be easier than that (though it might not have been for her, by that point, after having regarded math as torture for so many years).

Re: "advanced" math

[jinasphinx.livejournal.com]

I agree with you a thousand percent that it handicaps the kids. I saw this at N.'s kindergarten. The teacher had a chart on the wall of which homework assignments had been submitted, and to my shock there were a number of kids with no homework submitted. Not surprisingly, some of these were the kids having the most difficulty academically.