In a lecture in Science A-17, "The Astronomical Perspective," Professor of Astronomy and the History of Science Owen J. Gingerich spent about 40 minutes at tempting to explain the principles of escape velocity. But unlike most teachers Gingerich felt he had to illustrate the topic of the day. So he concluded his lecture by zooming out of Science Center D aboard a homemade rocket.

Gingerich managed to include a clever trick in each of his lectures--whether it was allowing each of the more than 200 students in the class to handle a chunk of plutonium or showing a film of an eclipse set to the tune of "Here Comes the Sun."

Many courses draw huge crowds because they are noted "guts." Others fill the largest lecture halls because they are required. But there are a few courses at Harvard that students flock to simply because they are "fun" to attend.

Gingerich is one of a rare breed of professors who take the time to sculpt their courses so that they entertain as well as instruct.

But there is more to turning a potentially dry subject matter into entertainment than just reeling off a series of classroom antics. So, what makes a professor an object of affection for students?

"I wouldn't dream of answering that one," says perennial professorial favorite Donald H. Fleming, Trumbull Professor of American History. Fleming, who teaches courses on European and American intellectual history, is known among students for both his interesting voice inflection and what students often refer to as the "charm" of his lectures.

In fact, students who take one of Fleming's courses are often so impressed that they end up taking at least one of Fleming's three other offerings in intellectual history.

When pressed to reveal the secret of his success, Fleming admits it is his "tightly organized" lectures and enthusiasm while teaching that draw the crowds. Nonetheless, he refuses to take all the credit and modestly suggests that it is the subject matter--intellectual history--that brings the hordes of students.

Possibly the most important indicator of his success is that no one has ever fallen asleep in one of his lectures, Fleming says, or at least, he adds, he hasn't noticed the dozing students. But he does try to observe the expressions of students during lectures to see how material is being received. "Every instructor has people chosen intuitively throughout the lecture hall to read their faces."

"People like my sense of humor in lecture," says Fleming. Students describe his humor as bawdy, but Fleming says his humor is rooted if, "the tone in which I discuss things." In fact, Fleming says he never tells jokes. "I can't remember them."

Another professor noted for exceptional teaching, Namburg Professor of Music Luise Vosgerchian, explains her philosophy. "There are two ways of educating," she says. The first is for the professor to devote his or her life to research and then present the results to the students who can then "accept or reject it," she explains. The second method, the winner of one of last year's Levenson Awards for outstanding teaching explains, is to diagnose the extent of the student's knowledge and "then proceed to challenge the student."

"I throw seeds to the students," says Vosgerchian, who taught two very popular music courses this year. In return, she looks for students to provide some imaginative input. "I am excited by the students' desire to discover."

Part of her success is due to the personal interest she takes in her teaching. Vosgerchian says she "tosses and turns" the night before every lecture because of her "intense desire to share" and the simultaneous fear that she might not convey her message to the students.

Vosgerchian makes an effort to get to know all her students personally, even in her large lectures. She says she knew every one of the 185 students in her fall semester 19th century piano music course. But sometimes getting close to students can produce out-of-classroom benefits.

Another popular lecturer is Thomas Professor of Divinity Harvey G. Cox, who this year taught "Jesus and the Moral Life" in the Moral Reasoning section of the Core Curriculum and a course on Latin American liberation theology. He credits his popularity to his use of visual and audio aids.

"I link what I am talking about with musical themes," says Cox. "Students associate what I am saying with some other dimension of the brain," Cox adds, explaining that students tend to remember facts by association. "I play the theme again, as students come into the classroom, and it gets them remembering."

Cox also uses cartoons, paintings and photographs displayed on a wide screen throughout his lectures, which commonly draw between 150 and 200 students.

"I consider myself a very good lecturer," concludes Cox, adding, "I love the performance element. Pacing, timing, voice intonation, and a lot of eye contact" are the key to his success, he adds.

Despite the professors' abilities as teachers, some students say they are drawn to these scholars' courses because of their relatively light workloads. For example, Fleming's courses commonly feature a midterm which does not count unless it boosts one's final grade. Fleming justifies his policy, saying he views the midterm as a "learning exercise."

Cox's course, "Jesus and the Moral Life," has the ever-popular attraction of omitting the final exam. The only requirements are a 15-page paper, a one-hour midterm and an uncommonly small reading load. "Some find my course easy, some find it rather difficult," Cox says.

When setting reading loads, Cox says he tries to pay close attention to what type of material he assigns rather than the volume. "Many students and teachers think of all reading as the same. The gospels should be read very slowly; students should ponder and think about it," he adds