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



I, too, have done a lot of work with "eled" and some work with in-ser=
vice teachers. My sister works in a grade school, so I know somethin=
g of the trade. Elementary teachers are not trained to be experts in=
anything other than children, and in the laws and standards regardin=
g teaching. Their highest priority is to make sure that the kids can=
read. The next highest is to teach 'em to add. Science is WAY down=
their list. In between, they have to satisfy mandates such as drug =
ed, sex ed, health ed, physical ed, and standardized test preparation=
. With everything else going on, probably an average of only two or =
three hours of the school day are spent on actual academic work. The=
y may have 35 children in the classroom, some of whom have severe phy=
sical and mental "special needs" and/or behavior problems, along with=
several adult aides, parent volunteers, and student teachers (all of=
whom also need supervision). Classroom teachers work with inadequat=
e resources, often buying hundreds of dollars of stuff out-of-pocket =
every year so that they have the basic supplies needed to teach with.=
They don't get prep time during the day. They do get to do lunchroo=
m duty, hall duty, playground duty, and bus duty. They don't have tim=
e or money for extras. If they do set up a science experiment, they =
have to keep 40 people occupied while they do so. It's no picnic. It=
's amazing that science gets done at all.
=20
I, too, deplore the lack of academic preparation of elementary teache=
rs in the areas of math and science. The in-service teachers I have =
met are anxious to learn how to teach science better. I will also sa=
y that because they are not experts in math, science, social studies,=
etc., teachers depend heavily on their curriculum for academic suppo=
rt. Therefore a good integrated science curriculum and coherent set o=
f teacher support materials is critical. IMHO, leaning on the textbo=
ok publishers to produce better-written, error-free materials would p=
robably accomplish more toward good science teaching than leaning on =
the teachers.
=20
Vickie Frohne

________________________________

=46rom: Forum for Physics Educators on behalf of Herbert H Gottlieb
Sent: Tue 2/22/2005 1:15 PM
To: PHYS-L@LISTS.NAU.EDU
Subject: Re: The bulb-with-one-wire task: too tricky?



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 a=
t
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 an=
d
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