Re: Order of E&M topics (was B and electric charge)

[John Clement <clement@HAL-PC.ORG>]

> The electrical force - and electrostatics - can be introduced as part of
> mechanics. David Hestenes of ASU Modeling Method fame, in one of his
> lectures. presented the vision of distinguishing and characterizing the
> various kinds and manifestations of force as a part - the final part - of
> the study of Newton's laws. The standard Modeling curriculum does not at
> this point realize this vision.
>
> Camp and Clement, in "Preconceptions in Mechanics", present a
> research-based
> and well-worked-out introduction to various manifestations of force:
> tension, compression including the "normal force", static and kinetic
> friction, and finally the gravitational force. Out of this they develop an
> effective treatment of Newton's third law, the failure to fully
> grasp which
> produces the "70% barrier" in most modeling physics classes - the
> inability
> of most modeling instructors to achieve higher than a 70% class average on
> the Force Concept Inventory (FCI). (Still way beyond what traditional
> instruction can achieve.)
This route is actually what is done with the Minds on Physics (MOP)
approach.  I find that it must still be supplemented with other materials to
get good gain.  When force is introduced they actually mix a variety of
common forces and treat them as "Empirical Force Laws".  The fundamental
forces are also mentioned, but deferred until later.  They us many of the
ideas from Clement/Camp and from other sources.

The 70% barrier may not be easy to break by any approach, especially at the
HS level.  The main reason is that my data shows that the scores on Lawson's
test appear to define the maximum gain that students can achieve.  Since HS
students have a greater mix of individuals with lower thinking skills the
maximum scores may be severely limited.  The only good solution to this
problem is to intervene in earlier science courses to bring up student
thinking.  Indeed the research of Shayer and Adey shows that an effective
intervention usually does not show results until several years later, so the
best time to intervene is in 7th and 8th grade.  6th grade my be too early
as some students may not have yet had the necessary brain development.  A
partial solution would be to deliberately incorporate cognitive enhancement
similar to Shayer&Adey as part of the physics curriculum.  My data also
shows that student gain correlates better with the Lawson posttest than with
the pretest.  This would seem to indicate that any thining increase due to
cognitive enhancement in physics has the effect of raising the gain scores.

Similarly I would advocate the Lawson test or some similar test can be used
to correct gain scores for comparison purposes.  This would make it possible
to compare various curricula without the bias introduced by the varying
thinking skills.  In private communication with a colleague I have found
that his students have an average Lawson score 2 points above mine, and he
has only 1 student in the "concrete" category, while I have considerably
more.  I am hoping that we can see if there is any consistency between our
results, and possibly confirm or deny my conjectures.

John M. Clement
Houston, TX