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On Wednesday at 11, the whole campus goes to class

A photo of a lecture hall, with balcony seating and large gothic windows.
This semester, GSS 201 is taught in McCosh hall.
Candace Do / The Daily Princetonian

Add-drop period ended this past Tuesday, and while some students may still drop classes before week 10, enrollment numbers are now more stable.

The Daily Princetonian collected data from the Office of the Registrar to analyze all 2,161 undergraduate classes. The ‘Prince’ looked for patterns in course intervals, start times, and times when the student body is in class simultaneously. The analysis shows classes clustered during the late morning and early afternoon, with over 4000 students in class simultaneously during the busiest time of the week.


A class refers to all sections registered with the Registrar, including lectures, classes, seminars, labs, precepts, and studios. The ‘Prince’ used the course times and enrollment data published by the Registrar, though some courses do not meet at their Registrar-scheduled times.

The Office of the Registrar has scheduled 33 unique intervals for students to register into classes. The most common time-interval for Princeton classes is in the block between 1:30 p.m. and 4:20 p.m. Dominated by seminars and labs, 4,569 seats are filled throughout the week during this interval. Other common class intervals include popular time periods for lectures and classes: 10 to 10:50 a.m., 11 a.m. to 12:20 p.m., and 12:30 p.m. to 1:20 p.m.

The earliest start time of 8 a.m. is shared by eight classes, whereas the latest start time for a class — 8:30 p.m. — is only for two lab sections for ORF 405: Regression and Applied Time Series.

While a roommate’s alarm for their 8:30 a.m. class may lead some think that there are many classes before 9 a.m., the most common class start times are 1:30 p.m. with 692 classes, 11 a.m. with 365 classes, and 10:00 a.m. with 237 classes. Other common start times include 12:30 p.m. and 7:30 p.m. Only 1,183 students are enrolled in a class that starts before 9 a.m. 


Across all the courses that start at 1:30 p.m., there are a total of 16,387 enrollments. This number exceeds the total student body because many students are enrolled in multiple courses that meet at this time slot during the week.

Some students who spoke to the ‘Prince’ prefer earlier classes to later ones.

“I chose my 8:30 a.m. class so I can have freer afternoons,” Asher Matthias ’27 said.

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The busiest start time for classes across the entire week is Wednesday at 1:30 p.m., with 211 classes starting at this time. The Registrar also schedules fewer classes on Friday afternoons and evenings compared to other days of the week.

“I like having my Friday afternoons free to enjoy time with friends or start early on work,” one student, David Wang ’27, told the ‘Prince.’

The University also accommodates religious requirements when it comes to course schedules. According to a Sept. 12, 2023 memo from Jill Dolan, Dean of the College, “Because the Friday prayer session overlaps with 12:30 and 1:30 classes, Muslim undergraduate students should have been rescheduled in classes, precepts, drill sections, and labs that meet at times other than Friday afternoon.”

Within each day, there are clear trends in class scheduling, with most students having breaks between classes throughout the day.  The ‘Prince’ broke down every 10-minute interval from 8 a.m. to 10:20 p.m. across each day of the week to see how many students were in class. The heat map shows that the most common times for students to have class are between 11 a.m. and 12 p.m. and from 1:30 p.m. to 4 p.m. 

This schedule enables most students to eat lunch between 12 p.m. and 1 p.m. while having time for homework, papers, extracurriculars, sports, and dinner from 4:30 p.m. to 7:30 p.m. Four classes meet during this block, when many athletes have practice: a precept for COS 126: Computer Science — An Interdisciplinary Approach and three Dance Studios for Dance Performance Workshop: Repertory I, II, and III.

The single time where the most Princeton students are in class is between 11 a.m. and 11:50 a.m. on Wednesdays, with 4,117 students enrolled in a class. From Monday through Thursday, over 3,900 students are enrolled in class between 11 a.m. and 11:50 a.m. each day, though this number drops to just over 1,500 on Fridays.

Most early-morning classes start on Monday or Wednesday, while classes that extend from 11 a.m. to 12:20 p.m. are relatively more common on Tuesday and Thursday. Night precepts and labs were more common on Tuesday and Wednesday than other days of the week.

There is also a distinct trend among the start times of various types of classes, with seminars and labs occurring far more often in the afternoon than other times of the day.

Among nearly all departments, lectures and classes typically occur earlier in the day, while labs occur at later times. The vast majority of seminars are held at 1:30 p.m., minimizing the opportunities for students to take other afternoon classes. Precepts are also offered both in the mornings and the afternoons, seemingly in an attempt to work around student’s busy schedules.

Just four evening lectures were scheduled by the Registrar: AAS 245: Introduction to 20th-Century African American Art, SML 312: Research Projects in Data Science [B], and both sections for VIS 265: Narrative Filmmaking I. Similarly, just 16 night seminars were scheduled, with 11 of these being freshman writing seminars.

Enrollment percentage did not vary significantly with class times, as most intervals hovered around 80 percent total enrollment. Out of start times with at least 500 students enrolled, 3 p.m. starts had the lowest enrollment percent at 71.55 percent with 8:30 a.m. starts just slightly ahead at 71.88 percent enrollment. 

Add-drop for undergraduate courses ended on Tuesday, Sept. 19. Students may drop courses for a $45 fee until Friday, Nov. 10.

Jack Prewitt is a contributing Data writer for the ‘Prince.’

Nathan Beck is a contributing Data writer and a staff Copy editor for the ‘Prince.’

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