Re: [Phys-l] crutches versus shoes

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

There is evidence from the  research that factor label should not be
introduced early.  It does interfere with the acquisition of proportional
reasoning, and it it is difficult to understand.  Actually it is easily
understook by students who have proportional reasoning, so proportional
reasoning needs to come first.  I am not sure what is meant by deep
understanding of proportional reasoning.  The tests for it are actually very
simple situations.  The Piagetian testing requires both the corrent answer
and correct methods.  In fact students are taught factor label way too soon.
So they think of the equation F_g=mg as being a conversion equation.

It is not bad after the acquisitin of proportinal reasoning.  Schwartz has
done research showing that early introduction of algorithms is bad for the
educational process.  But they can be introduced after some understanding
has been acquired.

John M. Clement
Houston, TX

>  a) Alas, some folks think the factor label method is a bad thing as 
>   a matter of principle, because it allows students to solve certain
>   problems without necessarily having a deep understanding of
>   proportional reasoning and scaling laws.