It's not a surprise that Social Analysis 10, "Principles of Economics," taught by Baker Professor of Economics Martin Feldstein '61, leads this semester's list of Harvard's largest classes.

But last year's second-place finisher Literature and Arts B-51, "First Nights," dropped to fourth, with enrollment decreasing considerably over the past two years.

Up from 808 last year, 827 students are officially registered for Ec 10, the full-year course that perenially packs Sanders Theater.

Moral Reasoning 22, "Justice" comes in a close second with an enrollment of 789. With 437, Science B-29, "Human Behavorial Biology" is the third largest course on campus, according to the registrar's Web site.

The enrollment for "First Nights" has fallen from 722 two years ago to 670 last year, and now, only 427.

General Education 105, "The Literature of Social Reflection" attracted 377 students, making it the fifth most popular course.

Ec 10, "Justice" and "First Nights" are held in Sanders Theater, which has a capacity of 1,166.

Interest in Science B-29, more commonly known as "Sex," exceeded the capacity of its 500-seat Science Center B lecture hall. Instructors held a lottery to determine who was allowed to enroll. The course hadn't been lotteried for the past two years.

Although only 9 percent of Harvard's courses enroll more than 50 students, the problems with such large classes are obvious.

"The drawback is really that the lectures don't cohere that strongly with the sections," said Scott G. Bromley '03, who is taking Ec 10. "The class covers a lot of very technical graphs and calculations, and that's impossible to do with 800 kids."

The head teaching fellow for "Justice," Joel Johnson, and Ruthmore Professor of Biological Anthropology Irven DeVore--one of the instructors for "Sex"--both said the sections in their classes attempt to accomodate for the difficulty of communicating detailed ideas to such large groups.

"Anywhere over 125 to 150 [students], the lecturer is giving a theater performance," De Vore said. "I learned this years ago. My strategy was just to sketch with very broad strokes basic theory and so on. The sections have been very important in this course for a long time."

Johnson mentioned that Justice's Professor of Government Michael J. Sandel incorporates student responses into his lectures as a method of increasing communication despite the intimidating size of the class.

"Even a class of 800 can be interactive," he said. "The professor doesn't have to just stand in front of the class and lecture. He can ask students to participate."

Nonetheless even Johnson isn't confident in the value of large lecture courses.

"I come from a small college myself," he said. "I'm a little bit skeptical about the overall benefits of large courses. There's a very limited amount of professor-student contact."