Following an interruption of course shopping by a blizzard last week, about 80 percent of undergraduates turned in their course study cards by Friday’s deadline, according to Faculty of Arts and Sciences Registrar Michael P. Burke.

Although administrators did not extend the study card deadline after the University closed for blizzard “Juno” last Tuesday, they said students, if necessary, could submit their registration materials until this coming Wednesday evening without a late fee.

Based on preliminary course enrollment data compiled from those study cards and published on the Registrar’s website, Harvard’s flagship introductory economics course has enrolled the largest number of undergraduates this semester.

As of Sunday, 535 students—531 of whom are undergraduates—were enrolled in the class, Economics 10b: “Principles of Economics,” taught by professor N. Gregory Mankiw. Last spring, the course ultimately enrolled 658 students.

Burke said the data is subject to change as the remaining 20 percent of students continue to submit their study cards. As students change their course schedules before the end of add/drop period, the Registrar’s Office will update the course enrollment statistics to reflect the movement.

From the preliminary data, Life Sciences 1b: “An Integrated Introduction to the Life Sciences” is the second-largest FAS course this semester, with 426 students enrolled as of Sunday, followed by Statistics 104: “Introduction to Quantitative Methods for Economics” with 320 students.

Computer Science 51: “Introduction to Computer Science II” is fourth-largest, with 305 students enrolled so far, compared to 259 students who took the course last spring.

“I’m excited that so many students are interested in the course,” said Computer Science professor Greg Morrisett, who teaches CS51 in Science Center C. “The hardest thing is finding a lecture hall… I wish we could have a bigger lecture hall and not drive people away during shopping week, just because there’s no seat for them.”

Morrisett attributes the course’s growth to the popularity of Computer Science 50: “Introduction to Computer Science I.”

“A lot of students had a good time [in CS50] and want to continue on doing CS,” Morrisett said. “I think that’s the primary reason [for the large enrollment numbers].”

Until the final course enrollment numbers are logged, classroom arrangements may fluctuate, according to Burke, who said administrators were “concerned that we wouldn’t get enough [study cards] to proceed with things like classroom assignments.” He called the number of students who submitted their cards on time “pretty decent.”

Teaching fellows also depend on final study card tallies to finalize their plans for each semester, according to graduate student Cristina V. Groeger ’08, a member of the Harvard Teaching Campaign who has served as a History department teaching fellow.

“Nothing’s really set until study card day, and typically when study cards are finally submitted you know how many [students will be in a course],” she said, adding in a follow up email that she expected that the delay in some students submitting their cards would “introduce more uncertainty.”

Dean of Undergraduate Education Jay M. Harris could not be reached for comment.          

—Staff writer Melissa C. Rodman can be reached at melissa.rodman@thecrimson.com. Follow her on Twitter @melissa_rodman.