Two years after a sequence of half-semester introductory courses first replaced each biology department’s individual introductory courses, faculty are still ironing out the details.

The courses, which span Biology 101 to Biology 104 and are known as “introductory modules,” are each half-semester courses that introduce students to an aspect of the biological sciences: biochemistry and biophysics, cell biology and membrane physiology, genes and development and ecology and evolutionary biology. They replaced individual biology departments’ introductory courses in the fall of 2012, in order to give students a more comprehensive overview of topics in biological sciences.

But the four required modules have caused their share of frustration, especially as more and more students enroll in them. This year, for example, some individual departments are discussing a potential revamp of requirements for certain majors, since many students who take the modules struggle to fit in all the other courses they want to take.

The modules, in the two years since they were first implemented, have affected many incoming students with regard to their science placements. Before 2012, students who received a 5 on the Advanced Placement Biology exam or an equivalent standardized test could place out of introductory biology courses — but with the change, students can only skip the modules if they also perform well on an accompanying University placement test.

The decision to switch to a more cohesive, year-long program was made not only to expose students to a broader foundation of the biological sciences, but also to give them more hands-on and experimental experience to complement the textbook material, said Molecular, Cellular and Developmental Biology Professor Vivian Irish, director of the modules. This includes reading of primary literature as well as writing research proposals, she added.

“We are placing a more explicit emphasis on the practice of biological research,” Irish said.

When the change was first announced, there was some trepidation, Irish said, but also excitement about the potential of the modules to offer students a fuller foundation for upper-level biology classes.

According to MCDB lecturer and module course coordinator Surjit Chandhoke, feedback has been positive. From what she has heard, students feel empowered that they can read and dissect primary literature, and are less intimidated going into upper-level courses. The experiment-oriented aspect of the modules has also helped give students an earlier jump on their own research, she added.

“Many of the students who have taken the modules started doing research as freshmen or sophomores — much earlier than the average student in previous years,” she said.

Students, however, expressed concerns about how difficult it is to place out of the modules, as well as their potential effect on the rest of their academic schedules.

Because students in previous years could place out of the introductory courses with their AP scores, they were able to take more courses in their place — for example, Kaleab Tessema ’14 was able to take a music class, and Antonia Gallman ’14 took graduate-level classes. The music class was one of Tessema’s favorite classes at Yale.

Now, students say they feel more pressed for space in their schedules. Sarah Merchant ’17, who earned a score of 5 on her AP exam, said she felt very well-prepared by her high school biology class and would have preferred to jump right into upper-level courses that match her specific interests. The inability to skip the modules put constraints on her schedule, she said.

“[The modules] take up one credit per semester, which means there’s even less space to take classes that you do more for enjoyment rather than to fulfill a requirement,” Kay Nakazawa ’17 said. “And there are already many requirements for science majors.”

To this end, administrators are still looking at what can be done to give science majors more freedom in class selection, Irish said. The University’s biological sciences departments have been adjusting the requirements for their majors in light of the additional coursework that the modules add on.

Last year, administrators also decided to offer all the modules in both the fall and spring terms. This change was implemented to account for high student demand and to decrease class size, Chandhoke said.

“Particularly after the first year of the course, we met as a team and went over the student reviews and the changes we were going to make to address the student reviews,” Chandhoke said. “We will always be looking to improve the modules and continue to tweak things.”

Nearly 400 students take the introductory modules every year.