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Teaching physics without a textbook?

Responding to:

I am puzzled by the conclusion that "those with no high school textbook
did much better in college than those with". How can this be interpreted?

he wrote:

.... namely that those who do not depend on textbooks may feel less
pressure to be a mile wide and an inch deep. Further, less dependence on
the book and its associated materials may be a sign of a teacher who is
pulling things from other areas, thereby increasing their field of vision.
Personnally, I would think that those who can teach without following a
text must have a good understanding of physics to be successful.

*********************************************************************

And here is a much longer comment. (My own opinion is at the end).

The evaluation of any textbook or tool must be based on the question,
"How does it contribute to the overall objectives?" I know of only one
example of effective use of a textbook in instruction, and that is by
Eric Mazur at Harvard. Mazur has the students read the textbook but he
doesn't go over the material in the text. When the students come in each
day, they must answer a question about what they have read, to see if they
have read the material. The question doesn't require deep understanding.
In his case, the textbook is a major source of knowledge. He assumes that
the students can read the textbook, and by and large Harvard students can
read textbooks. But not as well as you might wish, for the reading of a
science textbook is different. Most students don't realize that to be an
effective reader you must read with a question; they must be asking: "What
do I want to get out of this thing?" You don't just read one thing after
another.

I like the definition of a book by an old philosopher and linguist,
I.A. Richards. His definition of a textbook is "a machine to think with."
The textbook has a codification of information, and you must learn how to
get the information out. I have learned most of my physics from reading,
but this is a skill that takes a long time to develop; and we must help
our students to develop skills in reading. It is a non-trivial thing!

Unfortunately, textbooks are not written in a way that's conducive. You
have to understand the material in order to get what's in there; that's why
a physicist or physics teacher doesn't have much trouble. But the student
is unable to discriminate between the model and the peripheral things. The
models that we're considering are not unique to our program; these models
are inherent in all textbooks. But the models are BURIED in the textbooks.
To understand the textbook requires being able to RECOGNIZE THE MODELS.
This is acquired by long experience by physicists and physics teachers,
who develop these models implicitly, without being aware that they are doing
so. There's plenty of evidence that they have these models and use them.
A good example of the evidence is if you give physicists a projectile
motion problem. They don't read the whole problem before they do it. They
read one sentence and say, "Oh, that's a projectile problem." Then they
start drawing a diagram and solve the problem... They are SELECTING A
MODEL at the beginning, and that's what the students need to do; to ask,
"Is there a model here? and if not, do I need to make one?" THE MODEL IS
THE OVERALL STRUCTURE - WHICH THE STUDENTS DON'T SEE, IN TRADITIONAL
INSTRUCTION. And that's our objective. So I encourage people, if they have
effective ways of using a textbook, to tell us. But because of the way the
textbooks are written, many teachers find they are not helpful, especially
in high school classes.

Another message. I am not nameing the authors because I am not sure they
want to appear on phys-L.

***********************************************************************
I know that there are many people who feel that textbooks don't help them
in teaching their physics classes. However, it's my personal opinion that
we do our students a great disservice if we don't require them to use a
textbook at least some of the time. One of the goals that I have for my
students is for them to learn how to learn, and textbooks are a widely
available resource. Students need to be taught that reading a textbook
is not like reading a novel - you're not going to sit down and read it
from cover to cover and absorb it all. The skill that they need to develop
is going into a text to extract the appropriate information that will help
them in whatever problem they're trying to solve or question they're trying
to answer. Periodic assignments that specifically teach this skill will go
a long way in preparing our students for the learning ahead of them. I think
the question isn't whether you use a text or not,but *how* you use a text.

*************************************************************************
In my opinion a textbook is an essential learning resource at any level of
physics teachig.

1) Textbook is a common denominator. It shows teachers and students/parents
what should be learned in a given course.
2) Students are often confused why encountering new material. A possibility
to go over it, as many times as necessary, is essential to many of them.
3) Textbook is a source of homework problems.
4) A teacher may have good reasons to skip some material; she does not have
to be limited by what is printed.
5) Yes, "pressure to be a mile wide and an inch deep" should be resisted.
Some textbooks are better than others in promoting the "less is more"
idea; most of them have too much coverage.
6) Textbooks allow us to be innovative, for example, to teach without
lecturing and to focus on "discovery approaches", modeling, Socratic
labs, problem sessions, etc.
7) .........
8) ......
9) Teachig without a textbook can help an incompetent teacher to hide his
ignorance.
Ludwik Kowalski