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*To*: Ng Foo Keong <lefouque@gmail.com>*Subject*: Re: [xmca] a minus times a plus*From*: Mike Cole <lchcmike@gmail.com>*Date*: Sat, 6 Jun 2009 09:12:22 -0700*Cc*: "Ginsburg, Herbert" <ginsburg@exchange.tc.columbia.edu>, Galina Zuckerman <galina_zuckerman@hotmail.com>, Ricardo Nemirovsky <nemirovsky@sciences.sdsu.edu>, "eXtended Mind, Culture, Activity" <xmca@weber.ucsd.edu>, Noah D Finkelstein <finkelsn@colorado.edu>*Delivered-to*: xmca@weber.ucsd.edu*Dkim-signature*: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:reply-to:in-reply-to :references:date:message-id:subject:from:to:cc:content-type; bh=+uwYY3WTiVhQcLCCMbkErkJCVA08Bf5ugi0YSqEu3/c=; b=cCWNE39B9WBao+pe9tkqCH58E08QV61KF94bE42hlFUOAUzlFEFO9CbdXU8+1gnAsM UTHTnuL9yn7/Br+cwNaPkR3zo7M/p5lELZlQQx/ebtR/k3+lx0vYJAgaolLtoL+2+pTM U8IH4INWualP9doVqJgv+8jzHv8m8zBqgRe1A=*Domainkey-signature*: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:reply-to:in-reply-to:references:date:message-id :subject:from:to:cc:content-type; b=CvTOl/mVrmA7hsf0ucvT8wGB77tePHSqqhgW3SDWAhWw3xPwQ02aVZUq9cXOL4ziJV ZNVqAERERwj+1VGfBcRMlTKaTI/l/DNRNWt5R4eEkiC6W9gov3VnQVM2Y/gDWQmSHjhz ZTlOBxdm8CE0p4a+WnHbIYna1bJA7peDl4m+8=*In-reply-to*: <14a6419f0906060311u590630f6oa50d5bd2e5f0c17d@mail.gmail.com>*List-archive*: <http://dss.ucsd.edu/mailman/private/xmca>*List-help*: <mailto:xmca-request@weber.ucsd.edu?subject=help>*List-id*: "eXtended Mind, Culture, Activity" <xmca.weber.ucsd.edu>*List-post*: <mailto:xmca@weber.ucsd.edu>*List-subscribe*: <http://dss.ucsd.edu/mailman/listinfo/xmca>, <mailto:xmca-request@weber.ucsd.edu?subject=subscribe>*List-unsubscribe*: <http://dss.ucsd.edu/mailman/listinfo/xmca>, <mailto:xmca-request@weber.ucsd.edu?subject=unsubscribe>*References*: <000c01c9cc09$551bb160$ff531420$@edu> <005201c9cc4e$0abf89d0$203e9d70$@edu> <49FE597C.60904@mira.net> <30364f990905251757q6cc33970q7fc3e68d4f18fee9@mail.gmail.com> <4A1B4675.9000906@mira.net> <30364f990905252018t30880eb0i49bbadfa5a04fc87@mail.gmail.com> <14a6419f0906030610l24f0909bv87242d42986fb875@mail.gmail.com> <3B19033D3E2EC34C97DF364119A79A61D33DF3@EXVS1.its.uidaho.edu> <30364f990906040858q55f40166ja4d9f339d0245618@mail.gmail.com> <14a6419f0906060311u590630f6oa50d5bd2e5f0c17d@mail.gmail.com>*Reply-to*: mcole@weber.ucsd.edu, "eXtended Mind, Culture, Activity" <xmca@weber.ucsd.edu>*Sender*: xmca-bounces@weber.ucsd.edu

Hi Foo Keong-- It is so generous of you to even try to explain! And your question re math seems to me relevant to other areas of knowledge as well when you ask, "Can we condensefour thousand years of human development into an easily digestible four minutes for learners." Could we consider four years, just for whole numbers? Davydov starts with Algebra as the gateway arithmetic. Jean Schmittau, Peter Moxhay and others believe his method of introducing youngesters to math has some extra power. As I understand it, others on xmca are dubious and look to other sources of difficulty. Karen Fuson, in her article on "developing mathematical power ins whole number operations" focuses on introducing number operations through very simple, familiar, imaginable, events where exchange is involved. Its odd to me experiencing the cycle of time, the "coming back to the beginning and recognizing it for the first time" that is happening for me right now with arithmetic and early algebra. The source is quite practical with social significance: the unbridgable gap the children I work with face between what their teachers are teaching about (say) subtraction (2005-118 is my current keystone example) trying to get their kids to learn that the first step is to subtract 8 from 15 and know enough to treat the second zero as a 9. But the child, even understanding that the task the teacher is focused on is disabled because when asked 15-8 the answer =3 and only painstaking attention to the problem set up with fingers and subtracting one by one, with full compliance and even eagerness by the child, brings her to 7. Now suppose this phenomenon is ubiquitous, affects 100's of thousands of children, and is heavily correlated with social class. Then .... ??? .... I think my frustration is probably equivalent to yourse in intensity, but the quality is of a somewhat different nature. mike On Sat, Jun 6, 2009 at 3:11 AM, Ng Foo Keong <lefouque@gmail.com> wrote: > I was trained in mathematics at the University of Cambridge (UK) > for my undergraduate studies, concentrating more on pure > mathematics (including algebra). I am able to roll out a > rigorous abstract proof of why "minus times minus" is a "plus", > using only the basic axioms of real numbers (actually you only > need a few of those axioms). > > However, abstract proofs aren't likely to be useful for non-math > specialists and struggling neophyte learners of algebra. in > order to pull off such a proof, or even just to understand just > the few lines of proof, you almost need to be a mental masochist. > Who likes to go through mental torture? > > Can we condense four thousand years of human development of > mathematical understanding into an easily digestible four minutes > for learners? > > thus the huge gulf of understanding still persists. that's why > as an educator, i feel so useless being unable to help other > people. :-( > > F.K. > > > > 2009/6/4 Mike Cole <lchcmike@gmail.com>: > > I am currently reading article by Fuson suggestion by Anna Sfard on whole > > number operations. I also need to study Anna's paper with exactly this > > example in it. Not sure what moment of despair at deeper understanding > hit > > me. Now that I am done teaching and have a whole day to communicate > things > > are looking up!! Apologies for doubting I could have deep understanding > of > > why minus x minus = plus and minus x plus = minus. At present my > > understanding remains somewhat bifurcated. The former is negation of a > > negation as david kel long ago suggested, linking his suggestion to > Anna's > > comognition > > approach. The second I think more of in terms of number line and > > multiplication as repeated addition. > > Perhaps the two will coalesce under your combined tutelage. > > mike > > > > And member book links are coming in. Nice. > > mike > _______________________________________________ xmca mailing list xmca@weber.ucsd.edu http://dss.ucsd.edu/mailman/listinfo/xmca

**Follow-Ups**:**Re: [xmca] a minus times a plus***From:*Jay Lemke <jaylemke@umich.edu>

**References**:**Re: [xmca] a minus times a plus***From:*Ng Foo Keong <lefouque@gmail.com>

**RE: [xmca] a minus times a plus***From:*"Duvall, Emily" <emily@uidaho.edu>

**Re: [xmca] a minus times a plus***From:*Mike Cole <lchcmike@gmail.com>

**Re: [xmca] a minus times a plus***From:*Ng Foo Keong <lefouque@gmail.com>

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