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Re: Treatment of Negative Numbers
Posted:
Dec 4, 2012 2:18 AM
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On Sun, Dec 2, 2012 at 8:56 AM, Robert Hansen <bob@rsccore.com> wrote:
> BINGO! This is a must watch.
>
> The Max Beberman Film Collection Digitized
>
> Here are some of the films regarding negative numbers...
>
> http://glifos.cah.utexas.edu/index.php/MBeberman:E_mb_0002
> http://glifos.cah.utexas.edu/index.php/MBeberman:E_mb_0013
>
>
I watched the first one.
He starts with Left and Right and tries to say it's up to us which is which
but gets push back from the class when he tries to make right be left.
What he never talks about is how the very same road, seen from the other
side of the blackboard, has left and right reversed because the terms left
and right are relative to an observer. He does have one exercise where
what the girls call positive is the opposite of what the boys call
positive. But it's not because of standing on opposite sides of the road
("my right is your left" etc.).
Using town names at either end of the line implies an absolute way of
talking about direction (towards Shelbyville) whereas left and right are
relative to an observer. Draw a road on planet Earth somewhere. Which was
is "to the right"? Makes no sense really, to ask that. Most roads aren't
even straight.
He introduces positive and negative as if this solves the issue of adding
directionality but it does only along this one line. For Beberman, "out of
town" is one direction (because of one road) wheres most towns I've been to
have any number of radials one could call "outbound", not to mention up and
down (away from Earth center vs toward Earth center).
The emphasis on "just linear" is pretty mind-numbing. What if there's a
place not on the line you want to go? Sounds like you won't have a real
number, too bad for you.
And what about the fact that a road going to the left will eventually come
back around? If it's a road, it's on a curved surface. Does that matter?
Why does the line have to be straight, or does it? This is never
explained. Why not a curly cue line that intersects itself?
The kids are too muzzled, expected just to answer correctly as they're led
on into a somewhat inane discourse.
I felt sorry for these kids. We could say they're being educated but
they're also being dumbed down.
Kirby
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