Times and texts have changed.

It used to be that a pile of paperbacks was assigned reading for an English course, a sourcebook contained most of the articles needed for a Core class in historical study and a 900-page tome was the only way to wade through introductory physics or biology.

But the once clear-cut division between the type of texts used and fields may not be quite as clear anymore as professors report an increased use of sourcebooks across the board.

In fields as different as the hard sciences and the fine arts, professors say that the shift towards sourcebooks creates a different learning experience in the classroom as students are encouraged to construct their own understanding of the material.

"In my own sense, textbooks are not conducive to the classes that I teach because I like students to engage in the material themselves and probe the material for their own points of view," says Professor of the History of Science Everett I. Mendelsohn, who has been at Harvard since 1960. "A standardized textbook tends to predigest material."

Mendelsohn says that he looks for books or articles that have "a good story that is well-told."

"I like books or articles that make a point, that go from one place to another and that make the reader think about the material and the issues that are raised," he says. "What I use really are both articles and text that are specific to the substance of the class."

Like Mendelsohn, Professor of History Mark A. Kishlansky--who has been teaching for 23 years, the last six of which have been spent at Harvard--says he does not rely on standardized texts.

"I have never used a textbook in all the years that I have taught because I don't think that standardized texts are a good way for students to think critically about the past," Kishlansky says.

Kishlansky, himself the author of several textbooks, says his own textbook on Western civilization is used within Harvard's history department because professors often decide to use textbooks based on the nature of their course.

"Western civilization is the type of course where you do need a text because it is a course with a number of areas to cover," says Kishlansky. "I don't use textbooks for the kinds of courses that I teach because I don't teach survey courses."

In his seminars on 17th century England, Kishlansky says he tends to use five or six monographs--books on a single subject--to cover certain historical periods and sourcebooks to cover whatever material is left.

"It's very common in an introductory class, also called surveys, to use textbooks," he says, adding that math and science courses are especially conducive to textbooks.

However alumni say that it is just as common to use sourcebooks and commentaries in the humanities.

"Because so much of what I did was literature, I used mostly sourcebooks," says Joyce M. Greening '72, a Russian history and literature concentrator. "The only classes that I can remember that used textbooks were natural science classes, and even these usually had one textbooks and a number of assorted paperbacks."