Re: [Phys-l] workable versus unworkable energy

["John Clement" <clement@hal-pc.org>]

And what evidence is there that this works better than presenting the model
that energy can be transferred?  At least one of the major physics education
research groups, Modeling, is of the opinion that using this model helps
students visualize conservation of energy.

At present there have been no evaluations of competing methods of teaching
energy so there is no firm evidence for one method or another except for
observation and anecdotal evidence.

The matching work argument may work OK with formal operational students who
have good math background, but it is not obvious to lower level thinkers.

As far as the work argument goes internal or thermal energy can be
transferred without any perceptible working.

Of course by definition energy is not a fluid, but the idea of transference
is deeply imbedded in the human way of thinking.  It is a learned idea as
Piaget so aptly showed.  At certain levels of development children do not
understand it.  When understanding does happen, it is initially only for
concrete objects.  Now energy has a big problem, in that it is not a
concrete object, and can not be seen.  Anton Lawson has shown that concepts
which involve unseeable objects are much harder for students to understand
and he has even demonstrated that there may be a level of thinking,
theoretical, above formal operational where students can more easily
understand unseeable concepts.  This includes things like evolution, and
most physics concepts.  Only a small fraction (<20%) of graduating college
seniors test at this higher theoretical level.

So teaching energy is much easier when it can be made more concrete by using
a model that it behaves like a fluid in that it can be transferred.  However
when doing this, one must always put in front of the students that this is
just a way of visualizing it, or is an analogy.  The need for analogy and it
uses has been explored by John J. Clement and U.Mass Amherst in a number of
papers in JRST.  The purely abstract arguments based on working are very
weak for most HS and college students.

So there certainly is research which points in the direction of energy as a
fluid model to be the correct one for teaching.  But I will admit that there
is no research comparing the two different methods directly.  There is no
PER research that point in the direction of the more abstract method of
teaching.  Indeed, generally more successful teaching to this point has
generally used more concrete approaches.

But in the end, the working argument does not say that energy is or is not
transferred.  One can just as well think of working as the mechanism by
which energy is transferred.  So far the arguments hinge on thin semantic
arguments, which sound more like statements of belief.  Incidentally working
is probably a better term than work because the noun form implies to
students that work is a thing, rather than a change in a quantity.

There is research in how to teach these concepts, so I would suggest reading
some of it before trying to argue which method is better.

John M. Clement
Houston, TX

> > > you apparently don't totally agree that the property of energy
> > > >   is not transferable.
> > > > Apparently it has to disappear here and appear there, not
> transfer....
> > > >
> >
> > > But that is transference.  The word transfer implies that something
> > > disappears one place and appears in another.  For example you can
> transfer
> > > money by wire, or essentially teleport it.
> > //
>
> If listers would stop reifying energy -- with the excuse that it
> simplifies the discussion -- we would recognize that the discussion
> usually gets muddied when we do.
>
> Energy is not a fluid!!!  It is not "transferred"  etc etc.  The
> intensity of the property of energy can only be changed by DOING WORK!!!
>
> If we do work on one system we must also do work on a mating
> system.  This is the reason we get into the "transfer" problem.
>
> This is the clearest, simplest way to teach the youngens -- If only
> we could loose the Bill Nye teachings imbedded in us.
>
> And I am still looking to hear of a system which has the property of
> energy which can not do work.