Several months ago I was visited by the local sales rep for a major textbook publisher. I'll call him ``Bob''. Bob wanted to know whether I had any comments about his company's new introductory astronomy text.
``Yes,'' I said, ``but I'm afraid most of them are negative.''
Bob's jaw dropped. His eyes opened wide. ``Really?'' he said. ``You're the only person I've talked to who's had anything bad to say about this book!''
I find that hard to believe.
Every spring we professors are faced with the dilemma of choosing the text for next year's introductory astronomy classes, and every year our conversation sounds the same. Nobody likes the current text. Should we switch? To what? Has anybody looked at the other books on the market? Yes, everyone has, and they're all equally bad, so we might as well stay with what we've got.
Dissatisfaction isn't confined to us snotty professors; our students are equally frustrated. ``There's so much detail,'' they say. ``There's too much to memorize.'' Most frequently we hear the exasperated cry, ``I can't figure out how much of this is really important!''
You need only open one of the new textbooks --- any one will do --- to see why students are confused. There are color pictures everywhere, paragraph-long figure captions in italics, and tables and notes in the margins --- in blue. Boxes with supplementary material are set off to the side. The main text is crowded into a corner, and even there you're not safe from the dreaded ``keywords''. Try to read a sentence or two, and what happens? There's a reference to a figure. Look at the figure. What does it mean? Read the caption. Go back to the main text. Where were you? You've lost your place and have to find it again. There. But what's this? ``See Box 4.2.'' Read Box 4.2. Go back to the text. Here's a keyword in boldface. It's defined in the margin, but is it important? Better check the ``Learning Objectives'' at the beginning of the chapter. OK, back to the text again....
What's going on here? Surely a lot of care, thought, and hard work went into each of these books, and yet every one of them is a pedagogical nightmare. I see two unfortunate trends that are making the books less and less understandable with each new edition:
First is the use of color for the sake of being colorful. Color pictures are nice, but why do there have to be so many? The most complicated color photographs are barely mentioned in the main text, much less explained. Simple drawings are needlessly colorized, with absurd results. In one book, a beautiful painting illustrates the differential rotation of spiral galaxies; but inexplicably one spiral arm is tinted blue and the other pink. How many different ways are there for students to misinterpret this?
Second is the obsession with being up-to-date. Instead of familiarizing nonscientists with basic scientific ideas, textbooks are turning into technicolor encyclopedias. Unsuspecting students are suddenly asked to remember the difference between Wolf-Rayet and T Tauri stars, X-ray bursters and gamma-ray bursters, the s-process and the r-process, and Type I and Type II supernovae --- not to mention supergranules, superclusters, superconductivity, superfluidity, supersymmetry, supergravity, and superstrings. Honestly, how much of this is really important?
Since the 1970s, the average size of textbooks has been growing by 20 pages per year. Keywords are on an exponential rise --- a typical book now has more than 600. Students are paying more and more for these books, and professors are handing out longer and longer lists of what not to read. The books are only the tip of the iceberg, because nowadays every publisher's package includes overhead transparencies, slide sets, machine-readable banks of exam questions, simulation software, newspaper reprints....
Enough already! Our students are being introduced to astronomy the same way passengers on the Titanic were introduced to oceanography. This has got to stop. Authors and publishers need to remember a few guiding principles when designing textbooks for the future:
* The fundamental lesson of astronomy, and of all science, is that by careful observation and thought we can reach beyond ourselves and understand how the universe works. Everything else should be subordinate to that simple idea. We don't want merely to impress students with how extraordinarily clever astronomers are.
* A topic belongs in the book only if it illustrates a fundamental principle. Why, for instance, must every introductory text have a section on SS 433? What basic idea are the students expected to learn from it? That there are complex processes at the inner edge of an accretion disk? Who cares? And despite my own fondness for elliptical galaxies, I see no excuse for discussing a concept as esoteric as velocity anisotropy in an introductory text.
* Parallel subtexts should be used with extreme caution. True, certain material deserves to be set aside as optional, but some authors flagrantly abuse the supplementary box. Can't decide how to work an idea into the text? Put it in a box. The students will find it when they need it. Is that fair? An expert's understanding of a subject is a multidimensional network, but a beginner learns linearly, one thing at a time. Whether we're teaching a class or writing a textbook, it's our responsibility to forge a path that leads our students through the material in a coherent way.
I can hear the shouts of indignation starting already. ``You think you're so smart --- why don't you go write your own textbook?'' No, thanks. I'm not nearly so impressed with my writing ability that I think I could do a better job than those who have five or ten years' experience on me. Besides, imagine what my book would be like: short and cheap, without boxes and keywords. The only color pictures would be those directly related to the main ideas in the text. Everybody's pet topic would be left out: I'd include nothing on SS 433, or Stonehenge, or Seyfert galaxies. Everybody would hate my book, and no publisher would touch it with a ten-parsec pole.
And what about Bob? As I spouted forth many of these complaints, he took a lot of notes and seemed very impressed. He said that ``Glen'', the marketing director, would get in touch with me right away and added, ``We think your comments are very important.'' Then he left. And that was the last I heard from Bob, or Glen, or their company.
Somehow, I'm not surprised.