Unpredictable changes in class enrollment this year have confounded the process of assigning section leaders for the fall semester, drawing out professors’ concerns about larger section sizes.

Facing a projected budgetary deficit of $220 million last year, the Faculty of Arts and Sciences had planned this spring to cut 8 to 10 percent of the College’s section leaders for the fall semester, which was projected to save around $2 million, according Logan S. McCarty, assistant dean of Harvard College. But because of changes in enrollment, it remains unclear four weeks into the semester how much money will actually be saved or how section sizes will change.

“There is a lot of confusion and uncertainty about how large the sections will be,” said History Department Chair Lizabeth Cohen in an interview with The Crimson during shopping week.

Part of last spring’s budget plan had called for the hiring of fewer teaching assistants—section leaders who are otherwise unaffiliated with Harvard, as opposed to teaching fellows. Average section sizes were expected to creep upwards, closer to a long-standing target of 18 students, which, according to McCarty, is frequently undershot.

But with the new General Education curriculum now mandatory for freshmen, course enrollments in existing classes have seen dramatic shifts from prior years, and figures for new classes has proven difficult to predict.

Core classes have seen the most marked decreases in enrollment. Though McCarty said that decreased enrollment was expected, some courses dropped precipitously.

History Cores such as Historical Study A-13: “China: Traditions and Transformations” and Historical Study B-61: “The Warren Court and the Pursuit of Justice, 1953-1969” dropped from 122 undergraduates to 77 and 233 to 141, respectively.

Economics Professor N. Gregory Mankiw, whose introductory course Social Analysis 10 attracts hundreds of students each year, saw his enrollment decrease by nearly 10 percent from last year.

“The natural hypotheses are the Gen Ed requirements and recent macroeconomic conditions, as well as mere random variation,” he wrote in an e-mail when asked about the reasons for the downturn. “But I am not at all sure how to sort out which of these hypotheses is correct.”

Meanwhile, a new Gen Ed course co-taught by McCarty—Science of the Physical Universe 20: “What is Life? From Quarks to Consciousness”—was almost three times as large as expected, he said.

McCarty said final numbers regarding TF and TA hirings and section sizes will not be available until late October, when class registration closes and departments have submitted their final requests.

For the time being, Cohen said, she is hoping that section sizes will not see a larger-than-desired increase.

“It is very hard to have sections do what sections should do at larger than 18,” Cohen said. “I’d hate to see them get larger.”

—Staff writer Noah S. Rayman can be reached at nrayman@fas.harvard.edu.

—Staff writer Elyssa A.L. Spitzer can be reached at spitzer@fas.harvard.edu.