textbook revisions

["Robert J. Beichner" <beichner@NCSU.EDU>]

Ludwik Kowalski writes:

> The message form Roger Freedman prompted me to ask this
> question. How many authors of widely used introductory
> physics textbooks belong to phys-L? I would very much like
> to hear their side of the story of "perpetual misconceptions".
> Are they sufficiently free to discuss this in public? Are they
> allowed (by publishers) to start presenting material differently,
> for example, "energy before work", or "equilibrated charges
> on capacitors in series can be unequal", or "no need for
> Bernoulli", etc.

I've been a member of phys-L for a long time, although to be honest, I've
taken to just skimming the daily diaries. Publishers are interested, up to a
point, in talking about changing the way things are presented. Having just
finished a year and a half of 50 hour weeks (besides my regular University
duties) working with Ray Serway on the 5th edition of that calc-based book,
I can say that we were able to incorporate quite a few things that have been
learned from physics education research. Some of it is obvious. For example,
QuickQuizzes are questions that are interspersed throughout the text that
help students judge their own conceptual understanding. One "problem" with a
book that has been around as long as this one is that the text reads very
smoothly and the logic is fairly easy to follow. What happens is that
students can finish reading a section, think to themselves "That made
sense.", and then move on without really considering the material more
deeply. In other words, they don't realize that they don't understand the
ideas. Quick Quizzes get students thinking. They are often based on common
misconceptions. (The Instructor's Edition of the book has PER literature
citations for many of the Quick Quizzes. Jeff Saul is working on a very
detailed PER discussion for the Instructor's Guide.) Other changes to the
book are much more subtle. For example, in many places an introductory
paragraph or two has been added so that the need for a concept appears
before a name is given to the idea. For example, instead of starting out a
section with "Average velocity is defined as..." we set the stage by talking
about a car moving--with a table of numbers, a graph, and a drawing
(multiple representations). In the course of describing how the car is
moving, we say that a convenient way to discuss the motion is in terms of
how much distance the car covers in a given amount of time. We say that the
ratio of distance to unit time is so useful that it has been given a
name...etc, etc., You get the idea. It's Arnold Aron's "concept first, then
name." On casual reading, you might not even notice the change. The main
reason for this type of modification is for motivational purposes, but we're
also hoping that students will end up developing the idea that physics
concepts have been contrived by scientists as good ways of describing the
universe.

Other areas are much harder to change. Saunders did a bunch of surveys to
find out what chapters of this monster text could be dropped and which
chapters absolutely had to be kept. As you might guess, the two lists
overlapped completely! The decision was made to let individual faculty pick
what they wanted to cover from the full "banquet" of topics. One thing that
really impressed me was how careful the publishers were with making sure the
physics was right. I think this comes from their long history of working
with Ray. There must have been more than half a dozen very critical reviews
done of every single line of every single chapter. These were conducted by
physicists who generally had a specific interest in that particular topical
area. There were a lot of very subtle points that I had never worried about
(or in some cases, even knew about) that these folks brought up. There were
nearly 50 faculty members who were involved in the review process, and they
did an outstanding job. An interesting thought came to me in the midst of
one of our discussions on getting the presentation "just right." The
introductory physics texts, especially this one and Halliday, Resnick, and
Walker, are sort of the "archives" of our basic physics knowledge. I don't
mean that to sound like I've got a big head, it actually is a pretty
humbling experience. But think about it, where does anyone go to review some
fundamental principle of our beautiful science? Right to the intro textbook
they have on the shelf. I'm proud to have been part of the effort to keep
those ideas accurate and easily understandable.

Well, enough ramblings. Thanks for the chance to comment on what has kept me
"off the streets" for the past year and a half!

Bob Beichner
NC State