Hello Fernando,

Thank you for your response, appreciate your input too. I see!!

Yeah it helped.
....

?? How much of a damage was I inflicting on my'innocent' students,
who showed a lot of enthusiasm and interest? On trying to model the
drift vs conventional current; I pursuaded them to imagine/picture
a 'convoy'or long line of say 10 cars almost head to tail to each
other at a stop light and you can only see/picture a short distance
on either side of the stop light including that side where the cars
are, like you are taking a photo snap. You realise at time zero (when
cars are all stationary at the light) 'emptiness' or gap is to your
left, say, then when the cars starting to move to the left (where
emptiness 'is') they fill the space which was empty,
apparently 'emptiness' moves to your right? I later tried to perfect
my new found 'mental model' to saying supposing with the same case,
but to your left cars just move and stop to fill the space which was
empty, in other words cars just drifting (and stoping) to the left
where there is emptiness. I must admit, I could visualise what I
wanted to put across to kids, and my students showed a lot of
motivation and interest on this, what I thought was some 'creativity'
on my part. This SEEMED to work for the urban folks who sure enough
had no problem visualising what I was talking about. Then came a time
to teach in a rural set up, and (you can't believe it) some students
had not seen traffic lights but were my best and brilliant class
ever, (in real rural setups in a developing country) I used my
analogy, ALAS I could see some 'concentration lines' on the face of
most of my students. It was like someone had poured a whole bucket of
(very) cold water on me during winter. I was surprised, but i quickly
noticed I had to change my analogy to suit the rural folks. All this
was in the name of trying to excite students into understanding the
concept of drift and or conventional current as viewed against
electrons movement or drift. So I would argue to them that "take the
cars to be electrons and 'emptiness' to be the conventional
(direction of) current, now picture 'emptiness' moving in the
opposite direction to the cars. This was awesome to most of my
students. I still believe i was not doing the right thing, but I was
trying to right a model which has seemingly unconnected concepts.
I still believe I was doing the right thing, but there was something
terribly wrong with my analogy. Any ideas, comments or alternative
model for the conventional current.

Did this help on anything for my students then, or I should or
should have been then, summoned to the office of the Sec for
Education and Technology for damaging innocent brains?? [Take this
question here lightly, it's supposed to be for your giggles while you
think]

Are you making any sense of this? It would be easier when I explain
on the board or using powerpoint.

Thanks a bunch

Oppress B Makhafula
Zimbabwe


--- In learning-science-concepts@...,
fernando.espinoza@l... wrote:
> Hello Oppress,
> I believe the positive 'nature' of current flow is attributed to
Benjamin Franklin, whose scientific ideas were apparently better
known than his political ones for a time in Europe. I understand that
it is purely a matter of convention, I emphasize this with my
students so that they get a flavor for what humans do when trying to
understand nature. I hope this helps.
> Fernando Espinoza
> Science Education, Lehman College, New York, USA
> Physics and Astronomy, Hofstra University
> Hempstead, New York, USA
>
> [Non-text portions of this message have been removed]