The classes with highest enrollment for the fall semester have expanded beyond typical introductory lectures to include course offerings such as science classes for non-science majors.

Two of the most popular introductory courses, “Introduction to Psychology” and “Introduction to Microeconomics,” are scheduled at the same time this semester, and Christopher Udry, who teaches the microeconomics course, said he thinks the scheduling conflict caused a slight decline in enrollment for his class. But he said the variation was not significant and that his class consistently attracts a number of students slightly under 400.

“There’s many reasons people take [the course] and they vary across individuals, but for many students the course content is very fascinating,” Udry said. “It’s a really powerful set of tools.”

Milette Gaifman, who teaches “Introduction to the History of Art,” said in a Tuesday email that more sections were needed than she expected, and some students possibly dropped her class because of section confusion.

Yale College Dean Mary Miller said introductory courses are often large lectures because they attract many students who are inexperienced in a field and are curious to find out more about it.

“[The students] have never studied it, so they’re eager to find out more about what it means,” she said.

Geology and geophysics professor David Bercovici said that the number of students enrolled in his science course for non-science majors, “Natural Disasters,” has increased significantly from 2011 — the last time the course was offered — jumping from about 170 to roughly 350. He said he expected enrollment to increase because of the positive evaluations he received two years ago, adding that he thinks students were satisfied with the average workload.

Bercovici said he thinks teaching style is important to a course’s success and that he tries to “move around” during lectures, as well as engage his students through demos and activities.

“I get off the stage so that they don’t fall asleep,” said Bercovici.

But Bercovici said “Natural Disasters” is not a “gut class” and that students from all majors are attracted to it out of interest. He said he thinks students find the material challenging, given that the optional discussions sections are always full.

But Frederick van Hasselt ’16 said “Natural Disasters” is notoriously easier than other classes and that the large lecture format provides a feeling of anonymity for students who may be out of their comfort zone.

“I don’t have an aptitude or particular interest for science, so I prefer that anonymity that a large lecture has,” Van Hasselt said. “It is refreshing to find 400 Yalies who will admit that they are not good at something, which is what you are doing if you enroll in [Natural Disasters].”

All professors interviewed said they understand the necessity of having a sufficient number of discussion sections and quality teaching assistants. Udry said he thinks sections are fundamental for student learning.

“I spend a lot of time with teaching fellows, and we try to make sure people do not get lost,” said Udry.

Five students interviewed also agreed that the quality of teaching assistants in such large lectures is important. Andrea Barragan ’16 said the section dynamic can determine whether she chooses to take a large lecture.

Simone Paci ’17 agreed that the large lecture format can be advantageous. He said he was worried that “Introduction to Microeconomics” would be “too impersonal,” but he has enjoyed the course because the instructor encourages interaction and allows questions during class time.

Oct. 18 is the last day to withdraw from a fall-term course without it appearing on a student’s transcript.