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[Phys-L] Re: The bulb-with-one-wire task: too tricky?

My comments, shown in bold type and preceded with three stars *** and n
bold type, are interspersed in the paragraph below.


Joseph Bellina <jbellina@SAINTMARYS.EDU> writes:
I would guess that your grandchildren would be lucky since these
students now understand what guided inquiry is and how it works.

*** I certainly agree that Knowing and Understanding how "guided
inquiry works" is a valuable tool for college students who hope
to become science teachers.

They (the girls) can also explain how a circuit works in ways that
their boyfriend electrical engineers cannot.

*** It is difficult to believe that boys who have been graduated from
colleges with Electrrical Engineering Degrees have so much difficulty
with a simple series circuit containing only a bulb, a battery, and a
length of connecting wire.

Anyone would certainly be surprised to learn that graduate electrical
engineers were unable set up such a simple electric circuit. Is it
really possible that not even one, in a whole group graduate electrical
engineers, was able make a flashlight bulb light with the aid of a
battery and connecting wires.

They (the girls) are surprised when they hear their boyfriends saying
things that they know are obviously wrong.

*** Is it possible that the boys are only joking with the girls to get
their reactins? If so, the boys should mend their ways?


I don't think its fair, Herb, to criticize until you know more of
what is happening. If you were aware of the curriculum and had read my

note carefully you would have realized that this experience is the
beginning of their learning not the end.

*** I certainly did not intend to criticize anyone. It was just
that I have worked many years with graduate electrical engineers
and greatly respect them. Electrical engineering is very rigorous
and those who are graduaterd from colleges with earned degrees
in electrical engineering are among the most capable and intelligent
people that I know. I have never met even one of them who could not
connect a bulb and battery in a simple circuit..

... and cheers 2U2.

Herb
-------------- ------------------------ ------------------------
---------

Herbert H Gottlieb wrote:

Joe Bellina refers to his "preservice eleds" all of whom seem to
find great difficulty figuring out how to light a flashlight bulb
when given a battery and connecting wires. Is it possible that
these "eleds" are high school graduates who are close to being
graduated from a college ?

If so, what will happen to our country when they start teaching
our grandchildren???

Herb



On Tue, 22 Feb 2005 09:30:49 -0600 Joseph Bellina
<jbellina@SAINTMARYS.EDU> writes:


I don't think of this task as a test. It is rather a very good
engagement exercise. When my pre-service eleds do it, many go
through
three stages.
First, since most of them think of batteries and bulbs in terms
of
a
tranfer or delivery, they connect the one wire to the bulb and to
the
battery and of course nothing happens.
Then they note that the battery has two ends and begin to think
of
ways
to incorporate the two ends. Thats when they are likely to
connect
the
wire directly across the battery.
By the way, to forestall the uncomfortable hot sensation they get
at
the
battery wire connection I use somewhat worn out AA batteries,
which
will
still light the bulb but won't deliver enough current to make the
connection hot.
Once the figure they can't light the bulb by making one
connection
to
the bulb, I sometimes have to raise the question of whether or
not
there
are two "ends" of the bulb just as there are two ends to battery
and
to
the wire.
Eventually they find 4 different configurations to light the
bulb,
but
for them them the bulb is still a black box. This is a very
instrumental exercise, if I may use this philosophical term, the
only
really new insight is that there is a need for some sort of
circulation.

Just for the record , this is McDermott's Physics by Inquiry.

I think several things are happening in this exercise. First the
students are getting comfortable with bulbs and wires and
batteries.
Second they are beginning to see that a delivery model does not
work,
but that their actions are predicated on it. They begin to see
that
they need to think in terms of a circulation model.
It is a good place to begin, but not a good test since so many
pieces
have to go together to be successful. By the way, seeing the
bulb
light
is exciting for these students....so there is a nice reward for
success.

One other point. This year I gave a pretest that had a series of
pictures showing ways the bulb, wire, and battery might be
connected,
and asked them to predict which would light. The students got
about
half of them correct, with some configurations consistently
wrong.
However, the pretest seemed to have no effect on their ability
to
light
the bulb, because the process for the students was essentially
the
same
as it had been when I didn't give the pretest. They didn't seem
to
pick
up any clues for how to do it successfully, and it didn't even
give
them
clues on different ways to connect the three pieces together.

cheers,

joe

--
Joseph J. Bellina, Jr. Ph.D.
574-284-4662, 4968
Saint Mary's College
Dept. of Chemistry and Physics
Notre Dame, IN, 46556






Herb Gottlieb from New York City
A friendly place to live and visit




--
Joseph J. Bellina, Jr. Ph.D.
574-284-4662, 4968
Saint Mary's College
Dept. of Chemistry and Physics
Notre Dame, IN, 46556




Herb Gottlieb from New York City
A friendly place to live and visit