[IAEP] Abacus suggestions
walter.bender at gmail.com
Sun Oct 9 08:57:51 EDT 2011
On Sun, Oct 9, 2011 at 12:29 AM, Yoshiki Ohshima <yoshiki at vpri.org> wrote:
> For the first time I launched Abacus activity today. My impression is
> biased as I am Japanese and learned a version of it at school, but
> here is some suggestions:
> - The graphics lacks essential "dots". You see some dots in this
> picture for example: http://kamedake.com/_src/sc946/DSC_1976.jpg.
> These are "period" and "commas". The big white two dots means the
> it is 1's digit. The smaller dots on the bar are put every 3
> digits; even though the Japanese writing system would work better
> with comma's every 4 digits, we conceeded to westerners. In any
> case, missing these dots was the first surprise for me.
I wasn't aware of this. (We should update the Wikipedia article on the Soroban.)
> - As you can see, the default 1's digit (the big white dots) is in
> the middle, not the far right. That makes sense to tell that
> there are numbers smaller than 1 and for the idea of power of 10.
> (It is often a good technique to slide the decimal point, so I
> first thought the red triangle to mean this, but it is something
The red triangle is a mark found on many Chinese abaci. It is useful
for to keeping track of place while doing multiplication and division.
> - It trys to show the addition on the bar, but it defeats the whole
> point of abacus. Instead of showing:
> 700 + 10 + 7 = 717
> We would put just one number at each column and then the result
> should be self explanatory. (It would show "7 1 7" and it is the
This is a very good idea.
> - For a non-"5 and 4" abacus, this is not simple, but then why kids
> in the 21st century need to learn Mayan arithmetic...
My goal with the abacus was primarily to introduce the idea of
> - So, there are some 90 combinations of two one digit number
> additions. Some require 5's compliment arithmetic (adding 4 to 2
> is subtracting 1 but then adding 5, etc.) or 10's (if it is the
> right terminlogy.) Abacus was about building the muscle memory
> for these 90 patterns of additions. Some of these require you to
> move both index finger and thumb at the same time. After
> acquiring this muscle memory, you can do any additions without
> thinking, and that is the point of abacus. But now, "doing
> additions without thining" is easier with electronic calculators.
> At the same time, the Abacus activity is not set up for learning
> about this part of idea (and XO is not multi touch, so you can't
> build the muscle memory).
I haven't played with the abacus on the touch-screen XO yet... but it
is not multitouch. Muscle memory is not something we can do much with
on that hardware :P
> - However, it is still valuable to be aware fo the idea of
> understanding the idea of "adding 4 is adding 5 but subtracting
> 1", etc.
> - There is a bug when I tried to make my own abacus. If there is a
> number already on abacus, changing the board made some beads stuck
I thought I fixed that bug in a recent release. What version are you using?
Thanks for the feedback. Regards.
> -- Yoshiki
> IAEP -- It's An Education Project (not a laptop project!)
> IAEP at lists.sugarlabs.org
More information about the IAEP