After having done just a little research into the matter, I would like to
note that most of the major reformed curricula use g=9.8N/kg. In addition
they sesibly refer to the force due to gravity as F_g, and the acceleration
due to gravity as a_g (neglecting other forces). The notation would be to
use a for all accelerations, and F for all forces with appropriate
subscripts. This also avoids the confusion between N for normal force and N
for Newtons.
This provides a more coherent notation, and conceptual design, which can be
beneficial to introductory courses. Each of these steps alone does not
solve all problems, but combined they help the student achieve a coherent
view of physics, by reducing distracting confusions. In such a formulation
the constant g becomes initially a proportionality constant (pp 180 Workshop
Physics Activity Guide Module 1) which is determined experimentally, and
thus has the units N/kg. Modeling uses a similar scheme, and Minds on
Physics also use this scheme, to name a few other curricula. Essentially
the reform curricula have already switched, while conventional texts have
not. Incidentally I never see the confusion that all accelerations are
9.8m/s^2, since switching to more coherent notation.
This obviously does not solve the basic problem of low thinking skills. Low
thinking skills are attacked mainly by appropriate elicit, confront, and
resolve strategies. The confront part must show the student a surprising
result, but not too surprising or complex, so they can resolve it by
developing a new way of thinking (see Shayer and Adey "Really Raising
Standards". The change in notation including the definition of g make the
situation less confusing, which then allows the student to resolve the
thinking problems.
The equivalence of units is extremely dense to non formal thinkers, and
causes problems even when initially encountered by formal thinkers. Also the
common assumption that teaching formal logic fixes these problems, is false.
Informal logic and opportunities to think logically can be beneficial. For
an example of this problem see: http://www-cabri.imag.fr/Preuve/ICME9TG12/ICME9TG12Contributions/RouletICME0
0.html
Even after the students are enhanced to formal thinking levels, they still
need the coherent notation to help them make sense of physics at the basic
Newtonian level. Once they have achieved that, they can move on to making
connections with more advanced ideas. This is similar to the problem
students have with math. They fail to master the thinking needed to
comprehend simple problems, and then they are taught matrix algebra in
algebra II among other advanced topics. Needless to say they find it
confusing, and matrix algebra does not address the lower level problems.
The Benezit study referred to by Hake several times on this list highlights
this problem.
Now there are many teachers who will not acknowledge this problem. They
have a fixed paradigm about teaching that is not consistent with the
experimental evidence. It this they are similar to their students who have
an Aristotelian paradigm about how the world operates. Historical evidence
shows that many ideas are take up by the young scientists while the older
ones tend to resist the new ideas. Eventially the paradigm is changed, not
by converting the old, but rather by converting the young. A prime example
of this is the history of Boltzmann's ideas. Do we have to wait for a full
generation to have major improvement in physics teaching?