Re: [Phys-l] Paul Z's Physics book

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

I have looked at it.  It has had some input from the Modeling people, and it
does have sections on motion maps and kinematic graphs as a result, along
with the new mechanics.  But other than that it does not pay much attention
to the research.  Once graphs and motion maps have been introduced they need
to be used to solve problems, but instead they are only treated as
decorations for the usual algebraic methods.  Students should be given
problems which can not be solved easily by algebra, but are simple using
graphs or motion maps.  So the research based features are used as
decorations rather than substance.

In addition it has the usual array of confusing and misleading diagrams.
For example on page 323 the slope of the heating curve for water has the
wrong slope compared to that of ice.  As a matter of fact this graph is
rendered fairly useless in helping dispel misconceptions because it does
everything in K rather than C, and the breaks in the graph mislead the
student into thinking that the it takes more energy to heat water from 0 to
100 than it does to convert an equivalent mass to steam.

It seems to lack coherence, and is again the typical one damn thing after
another book.  By presenting formalism first and concepts second, the
concepts are eviscerated.  But of course most texts do that, except for
certain unique examples.

Another example of a bad graph is the one on page 90 where 15 of the points
lie on the line, or above the line, except for 2 near the endpoints.  The
line of best fit is a lousy one.  It is even worse on pages 15,16, 18 where
all data points lie above the line of best fit.  They also have a broken
scale which only encourages students to use nonlinear scales.  Artists love
to draw all graphs at 45 degrees with the lines going through the grid
lines.  This habitual practice is probably a contributing factor to
student's not being able to estimate graphs correctly.

Apparently artists and proofreaders need a good dose of Feuerstein
Instrumental Enrichment to promote a need for accuracy and precision.

And of course Newton's laws are presented in the correct numerical sequence,
which is totally the wrong sequence to build understanding.  In particular
NTN3 needs to be introduced first as an interaction.  Then there is the use
of Fgrav = m g where g = 9.80 m/s^2 which is confusing as heck to students.
The U.Mass Amherst PER group has been quite emphatic on this point.  Since
it comes from the gravitational law, g=9.8 N/kg, which also helps the
students understand the concept better.  Then it makes the common mistake of
putting the at rest case before the constant motion case of NTN1.  Students
believe the at rest part, and totally disbelieve the constant motion part.
There are ways of presenting these things to help students believe them, but
there is no support for helping students with their misconceptions.  Anchor
and bridging analogies is one method that can be incorporated into a text.

In all fairness a text which actually promoted inquiry, and which brings out
the evidence before giving the pat formulas, would probably be longer, and
would also have poor sales.  Teachers want texts that look good to them, and
that cover all material.  Parents like texts that have colorful pictures
that make the presentation attractive.  Unfortunately the evidence is that
the pretty pictures can be distracting, and simpler representations may work
better.  After all the name of the game is to sell books first.

So the fact that it emphasizes principal rays in ray diagrams is certainly
in line with other texts, but promotes misconceptions about lenses and
mirrors.  McDermott et. al. has written on this topic as I recall.

John M. Clement
Houston, TX



My read is quite different -- their complaints are quite cogent and 
specific.  It didn't appear they wanted to be spoon fed, just not 
misled.  It does appear they are discussing two editions.

bc

Sam Sampere wrote:

> Gee, based on those reviews, it sounds to me like he got it right! These
> HS students who wrote the reviews seem to want to be spoon-fed. Oh, like
> many of the students here! Or at your institution! 
>
> I haven't seen the book, but I wouldn't pass judgment based on those
> comments.
>
> Sam
>
>  
>
> > Can someone comment on the 2005 edition of Zitzewitz's Physics:
> > Principles and Problems book from Glencoe?  In particular, has it
> > greatly improved over the previous versions?  
> >    
>
> I have no first-hand knowledge of the 2005 edition .....
> but I observe that the customer reviews on amazon.com are
> as bad as you would expect based on previous editions: