Introductory Science Courses Challenge Class Capacity

93 students enrolled in CHEM-155 last fall and 87 registered for BIOL-191 this spring — numbers that stand out at a small liberal arts college where 83% of classes have fewer than 30 students. This came as a surprise to students expecting more moderate enrollment.

“It was a little funny, coming in and expecting small classes — you’re choosing a college with a 7:1 student-to-faculty ratio. Then you walk into that lecture, and it’s so many kids,” said Evan Yang ’26, reflecting on his first-year science courses at Amherst.

While introductory courses traditionally draw larger rosters, this year’s enrollment trends raise questions about course sectioning and placement structures and highlight growing global interest in STEM. Faculty and students reflected on the implications of high enrollment and potential adjustments moving forward.

“Part of the Amherst experience is about being in classes of 10 or 15 or 20 — maybe not for every single class, but as often as you can — to really get those kinds of intimate interactions. The reason why I come to work every day is to get to talk to students, hopefully in small groups,” reflected Department Chair of Biology Ethan Clotfelter.

For the chemistry department, the high enrollment wasn’t entirely unexpected.

“Historically, a quarter to a third of incoming students have taken intro chemistry their first semester,” said Department Chair of Chemistry David Hansen. “We have had the sum of [enrollees in CHEM-]151 and 155 be over 100 for years and years.” Introductory chemistry is required for pre-med students and those majoring in chemistry, biology, biochemistry & biophysics (BCBP), or neuroscience.

Students are placed in CHEM-151 or CHEM-155 based on their previous coursework in math and physical sciences. To accommodate varying distributions of students between 151 and 155, the lab sections of the two courses are combined. This eliminates restraints on class capacity, ensuring that students can enroll in a course best suited to their academic background and avoid lab space constraints.

“We’re really looking to give students a good introductory college chemistry experience the second they set foot on campus,” said Hansen. “We look at every single student and put them where we think they belong: in [CHEM-]151 or 155, and rarely even directly into organic chemistry.”

In recent years, more students have placed into CHEM-155 than in CHEM-151, but the gap reached its widest this year — 93 students in 155 compared to just 43 in 151. While the imbalance raises logistical questions, Hansen emphasized that proper placement takes priority over class size distribution.

“We have talked in a general sense of, ‘If the balance of more and more incoming students being placed into CHEM-155 keeps tipping, should we reimagine the way we structure intro chem?’” he said.

The department has considered alternatives to even out enrollment in each section, such as offering multiple lecture sections of 155 or reconfiguring the course placement system altogether.

Similar debates have taken place regarding organic chemistry. The first semester course, Organic Chemistry I (CHEM-221), had 88 students this past fall and 31 in the spring semester. Organic Chemistry II (CHEM-231) had 19 in the fall and 71 in the spring. The department has previously experimented with offering multiple lecture sections but ultimately decided to maintain a single large section.

A key reason for this is the potential for comparison between sections. “At schools that do have multiple lecture sections of the same class, there is often a lot of talking among students about which is the best section.”

The biology department faced a similar challenge with BIOL-191. 191, the introductory course to molecular and cellular processes, is required for students planning to major in biology, neuroscience, or BCBP.

“We were expecting around 80 [enrollees], and then we got 104 or 105, so that caused a little bit of panic because it’s not a great educational experience,” said Clotfelter.

Clotfelter noted that an increase in the number of students majoring in science fields, a trend seen nationwide, may underlie this rise in enrollment: “The number of students per year who major in either BCBP or neuro or bio has increased from around 60 per year, 10 to 12 years ago, to around 80 to 90 per year now. Students in those three groups all have to take 191.”

“We spent a lot of time trying to figure out, ‘Do we split the course in half? What are some things that we can do to make the average class size smaller and to make the student experience better?’” reflected Clotfelter.

Until recently, BIOL-191 was only offered in the fall, with enrollment consistently exceeding 100 students. The department’s decision to offer it in both semesters has helped redistribute demand — enrollment now typically sits at around 40 students in the fall and 80 in the spring.

However, this spring’s enrollment surpassed expectations. With four lab sections capped at 24 students each, the department initially worried about accommodating everyone and urged prospective students to consider postponing the course to the fall, placing out of BIOL-191, or taking BIOL-181, another introductory biology course.

“Some students came to the first day of class and said, ‘This isn’t really what I wanted,’” said Clotfelter. Ultimately, enough students opted to switch into BIOL-181 or delay 191 until a future semester that no one had to be dropped.

“I feel like it’s a much more pleasant, intimate, and ultimately beneficial educational experience, offering [BIOL-181] to a smaller class,” said Clotfelter, who teaches BIOL-181. As a response to the high BIOL-191 interest, the department offered BIOL-181 — usually only offered in the fall — this spring.

Both current students and those who have already completed the introductory science courses shared their perspectives on how class size shaped their learning experiences.

"[Big classes are] a little intimidating. Nobody really raised their hand at all, which is less of an issue in smaller classes,” said Yang.

Some students have enjoyed their experience in a larger course. “It’s been cool to meet so many people because of these larger lecture-style classes,” said Kaitlyn Huang ’27, who took CHEM-155 this past fall. “I have not felt like being part of such a larger lecture-size class made things any less personal. In fact, I was really, really impressed by how the professors, even with so many students, are still so willing to give you personal time.”

Emmett Murphy ’28 echoed a similar sentiment regarding his experience in CHEM-155: “It reaffirmed my choice in going here ... even the larger classes feel pretty personal.”

Students also underscored the importance of professor outreach in these large classes: “If the professors are urging you to seek help and tell you that even though you’re in a big class, they still want to talk to all of you, that makes a huge difference,” said Gina Durazo ’26.

Professor accessibility, in addition to smaller discussion sections and labs capped at 24 students, can help personalize learning experiences.

Despite increasing enrollments in introductory STEM courses, both Clotfelter and Hansen emphasize Amherst’s dedication to strong student-faculty interactions and an intimate liberal arts education. “Amherst really does recognize the importance of teaching and honors the time it takes to be a good teacher,” Hansen said.