[IAEP] Abacus suggestions

[Yoshiki Ohshima]

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.

  - 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
    else.)

  - 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
    result.)

  - For a non-"5 and 4" abacus, this is not simple, but then why kids
    in the 21st century need to learn Mayan arithmetic...

  - 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).

  - 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
    outside.

-- Yoshiki