No academic catalog is going to define an undergraduate class as a “weed-out” or “gatekeeper” course. But these courses can come to define individual career paths, pushing some students out of STEM fields entirely.
The weed-out effect impacts students of all backgrounds, but students from marginalized groups, especially Black and Latinx, are particularly hard hit, and experts say these weed-out courses are part of the systemic racism underpinning the diversity challenges that chemistry and the sciences overall face. In addition, these same students may struggle to develop a sense of belonging in STEM (C&EN, July 20, 2020, page 26).
In an effort to characterize weed-out courses, researchers at the John N. Gardner Institute for Excellence in Undergraduate Education came up with a standard definition of such courses (New Dir. Higher Educ. 2017, DOI: 10.1002/he.20257). They are high-enrollment foundation classes usually taught in a lecture-based format. These classes have high DFW rates, meaning that many students in these classes receive Ds or Fs, often because of grade curving, or withdraw from the course. In the sciences, these classes are required for majors, often in departments other than the one offering the course. Researchers at the University of Colorado Boulder used the same definition for their study Talking about Leaving Revisited, a 2019 update of a study originally published in 1997 (2019, DOI: 10.1007/978-3-030-25304-2_7).
That general chemistry and organic chemistry courses at many institutions fit this description should come as no surprise. In their analysis of the course offerings at six institutions, the authors of Talking about Leaving Revisited found that 22% of the courses meeting their criteria of weed-out courses were chemistry courses. A study by the Gardner Institute of introductory chemistry courses at 31 institutions, including community colleges and public and private 4-year colleges and universities, found an average DFWI (including incompletes) rate of 29.4%. The DFWI rates for Black and Latinx students in introductory chemistry at the 31 institutions were above 40%.
This disproportionate effect happens because students from marginalized groups are more likely than other students to have attended high schools where advanced math and science classes weren’t offered, experts say. Such students with an interest in STEM (science, technology, engineering, and mathematics) majors lacked opportunities that students in high schools with more resources had.
“We have students who, because of America’s version of apartheid, are not ready to go into a regular STEM degree that could get them out in four years,” says Cheryl Talley, a neuroscience professor at Virginia State University.
“If students haven’t taken chem and physics in high school, they really come to the university with a disadvantage in terms of their likelihood to choose a STEM major and to persist in STEM majors,” says Angela Kelly, a physics education researcher at Stony Brook University who has studied student access to math and science courses in high school. “The lack of access at the precollege level is a particular issue that is just not getting the attention that it needs.”
A lack of preparation can affect students at any university. But, rather than pinning blame on struggling students, faculty should look inward and recognize that their institution’s inability to adapt to changing demographics is usually the heart of the problem, according to Dorian A. Canelas, associate professor of the practice of chemistry at Duke University (ACS Symp. Ser. 2015, DOI: 10.1021/bk-2015-1193.ch002). When Canelas joined the faculty of Duke University 11 years ago, general chemistry was taught in a way that immediately launched into thermodynamics of reactions, under the assumption—not always a good one—that all the students had had a year, if not more, of chemistry in high school.
“Every year we have about 50 students who have had less than a year of chemistry education” before enrolling at Duke, Canelas says. “It was absurd what we were doing to them, but it was such a small percent of the students that it was easy to label the students as the problem.” The practice was affecting students from marginalized groups the most because they were more likely to have attended high schools without a chemistry teacher.
By the numbers: Weed-out classes
22%: Classes, in a study of six institutions, fitting the definition of weed-out classes that are chemistry classes
29.4%: The average rate of students who receive grades of D, F, or incomplete or withdraw from introductory chemistry classes at 31 institutions studied by the Gardner Institute
Source: Talking about Leaving Revisited, Gardner Institute.
Note: Numbers refer to US institutions.
Working with Richard MacPhail, another Duke chemistry professor, Canelas designed an introductory chemistry course that did not presuppose high school chemistry (J. Chem. Educ. 2014, DOI: 10.1021/ed400075n). Canelas considers it an entry-level course, in the same way that beginning foreign language courses are entry level rather than remedial. The class uses active learning approaches and problem solving to introduce concepts such as stoichiometry and compound naming. The course does not include a lab, to prevent students from enrolling in a course not commensurate with their backgrounds.
After completing the course, students can then go on to regular general chemistry, which continues to start with thermochemistry. Following the curriculum reform, students who started with the introductory course did as well in organic chemistry as ones who started in the traditional general chemistry course. In fact, some students who started in the introductory course have gone on to be summa cum laude graduates in chemistry.
Often, professors turn a course into a weed-out course by teaching too much material too quickly. Such a push leads to what Timothy J. Weston, a research associate at CU Boulder’s National Center for Women and Information Technology and one of the authors of Talking about Leaving Revisited, calls irrelevant or constructed difficulty. Subjects such as chemistry that deal with many abstract concepts already have intrinsic difficulty, but “when you try to cram everything into a certain amount of time, you teach it poorly,” he says.
“The problem with traditional intro courses is that they’re a mile wide and an inch deep, so they teach way, way too much,” says Melanie Cooper, a chemistry professor at Michigan State University. “Students just get these fragmentary bits and pieces, and then they’re tested on fragmentary bits and pieces. It’s not useful, so they can’t apply it to any other system.”
And because of the way that general chemistry is taught, it can become a de facto applied math course. When Suazette Mooring of Georgia State University studied students’ understanding of the concept of acid–base equilibrium, she found that some students could solve problems even though they didn’t fully understand the concept. “Those students are making A+ in the class, not because they really understand the concept of chemical equilibrium, but because they can do the math,” she says. “We may be filtering out students who may be able to thrive in chemistry if we focus more on the conceptual part of it and not make it a math course.”
Grade curving, which guarantees that a certain percentage of students will receive low grades, contributes to those high DFW rates that define weed-out courses.
“When I think of a weed-out course, there are arbitrary barriers that are put in place to keep students out. One of the most common and egregious, in my opinion, is grading students on a bell curve,” says Thomas Freeman, an assistant teaching professor of chemistry and director of the Chancellor’s Science Scholars Program at the University of North Carolina at Chapel Hill. “If you learn the things that I ask you to learn and you show that you’ve learned them, then you can get an A. And if everyone does that, then everyone gets an A.”
Grade curving “has been going on for years and years. It’s gotten baked into the culture that this is how you keep rigor up,” Cooper says. “I’ve always been adamantly opposed to curving grades. It feels like an admission of defeat.” By curving grades, she says, professors seem to be saying that it’s alright not to succeed in teaching the material to 20–30% of students.
Instead of curving grades, Cooper advocates clearly defining the desired learning outcomes. “If we say these are the goals and this is how students will meet them, then I don’t have a problem with everybody passing and everybody making a good grade, if we all agree on what the standards are,” she says.
Some chemistry professors are finding ways to transform their classes and improve student outcomes.
For example, Michigan State introduced a transformed general chemistry course called CLUE (Chemistry, Life, the Universe, and Everything) in 2013. CLUE, which is designed to align with the Next Generation Science Standards used in some K–12 schools, focuses on cross-cutting concepts, core chemistry concepts, and scientific practices and emphasizes the use of knowledge instead of memorization and rote problem solving. Since it instituted the new curriculum, the DFW rate has declined. More than 700 additional students each year are able to move on to the next course in the chemistry sequence than would have under the traditional curriculum, Cooper says (Sci. Adv. 2018, DOI: 10.1126/sciadv.aau0554). Students who took CLUE do just as well in organic chemistry as students who took the honors section of general chemistry (J. Chem. Educ. 2019, DOI: 10.1021/acs.jchemed.8b00784).
Another strategy that has proven effective is permeating the student experience with activities that encourage students to develop their metacognitive skills—that is, thinking about what they learn and how they learn it.
At Oklahoma State University, Jacinta M. Mutambuki combined active learning and lessons in metacognition in a general chemistry course (J. Chem. Educ. 2020, DOI: 10.1021/acs.jchemed.0c00254). “My idea was not to wait until they do an exam to really teach them how to study,” she says. She taught them about metacognition early in the semester and suggested strategies for learning the material. Then, in conjunction with exams, she asked students to assess their exam preparation and the study strategies they would change to excel in the course. Students in a class that combined active learning and metacognition performed significantly better than did students in a class that used active learning without explicit metacognition lessons, especially on cognitively demanding chemical concepts. In addition, the combination of active learning and metacognition resulted in lower DFW rates than active learning alone.
Clarice Kelleher, Benjamin Turnpenny, and their colleagues at Binghamton University slashed the DFW rate in general chemistry by adopting metacognitive approaches. They identify at-risk students with a diagnostic pretest at the beginning of the semester. They invite students who score below 50% on the pretest to join a program called the ACTIVE (Applying Critical Thinking in Various Elements) Center, in which they do online math and chemistry tutorials and participate in weekly sessions focused on study skills, critical thinking, and scientific reasoning. The ACTIVE Center has helped drive the DFW rate at Binghamton below 10%.
Providing opportunities for cooperative learning in which students learn from each other can also reduce the weed-out effect. At Virginia State, Talley developed a program where advanced undergraduates mentor freshmen and model successful behaviors. The mentors regularly check up on their mentees and report to the professors. Those interactions are “where the magic happens,” Talley says. “We slowly by slowly over the course of a year shift the behaviors, the attitudes, the beliefs of these students and turn them into students who know how to be students.” Eighty-five percent of the students who have gone through the program have graduated with STEM degrees, Talley says.
Another cooperative learning approach involves flipped classes in which content delivery happens outside class in videos or guided readings. In class, students work on problems, individually or in groups.
Mooring, at Georgia State, teaches organic chemistry as a flipped class. Once a week, she uses peer-led team learning, in which groups of students work with advanced undergraduates who have already taken the course. In qualitative student surveys, Mooring found that combination of the flipped format and the peer-led team learning improved students’ emotional satisfaction with the subject and the intellectual accessibility of the material. The overall DFW rate went down (J. Chem. Educ. 2016, DOI: 10.1021/acs.jchemed.6b00367).
But the aggregated data masked persistent gaps. In a follow-up quantitative study, Mooring and her collaborator Jennifer Lewis of the University of South Florida found a gap in gains in emotional satisfaction with organic chemistry between Black women and other students although the Black women’s grades had also improved (J. Chem. Educ. 2019, DOI: 10.1021/acs.jchemed.9b00516). “Overall, it still had an impact, even though there was a gap,” Mooring says.
Senetta Bancroft, a chemistry professor at Southern Illinois University, decided to flip her class after having a semester with low average exam grades. She encouraged student attendance and participation by pegging part of students’ grades to group performance during problem solving. Over the course of a semester, students worked more problems than they would have if problems were assigned only as homework, Bancroft says.
Bancroft saw a significant improvement in grades, especially for Black and Latinx students (J. Chem. Educ. 2019, DOI: 10.1021/acs.jchemed.9b00381). “I expected them to do significantly better but not to the point where it was going to make the differences evaporate statistically,” Bancroft says.
The Gardner Institute is working with colleges and universities to transform large enrollment courses with high failure rates from gatekeepers to gateways, through its Gateways to Completion program. So far, nearly 100 institutions have participated in the program, says Andrew K. Koch, the institute’s president and chief operating officer.
The choice of the word “gateway” was intentional. “When we started doing work on foundation courses, we didn’t want to unintentionally promote the belief that these should be weed-out, should be gatekeepers,” Koch says. Instead, the institute focuses on course and curriculum redesign to change the narrative from one of weeding out and gatekeeping to one of gateways.
Eastern Michigan University is one of the institutions that has revamped its first semester general chemistry class (CHEM 121) as part of the Gateways to Completion program (ACS Symp. Ser. 2019, DOI: 10.1021/bk-2019-1341.ch002). Before the changes, EMU had an average DFWI rate of more than 30% across all sections of CHEM 121, according to Amy F. Johnson, who led the efforts in the chemistry department. As part of the project, the department increased the math prerequisite and agreed upon learning objectives for all faculty to implement. The department also extended the class period by 30 min to accommodate supplemental instruction, in which advanced undergraduates work with current students. The changes have reduced the DFWI rate in CHEM 121 to about 20%. There’s still work to do: although the overall DFWI rate decreased, the rates for marginalized groups did not decrease as much.
The department has used its data and faculty discussions about pedagogy to encourage the adoption of active-learning methods. “We’ve seen a lot of our faculty, even those who were pretty rigidly lecture based, start incorporating new things because they’re hearing other people talk about it with passion and enthusiasm,” Johnson says.
But transformed chemistry courses represent just a small fraction of the undergraduate chemistry landscape. Many others continue to act as weed-out and gatekeeper courses that force students to abandon their plans for STEM careers. Much of the damage is inflicted not by ill intentions but by people ignoring how course structures lead to inequitable outcomes.
The situation won’t improve “until we start to recognize and acknowledge that there are racist and classist systems at work in a lot of our structures in education,” Koch says. “They manifest themselves at a great scale—because of the numbers of students who take these courses—in gateway courses.”
Bancroft has hope for the future of chemistry education, but she sees plenty of room for improvement. “A lot of us are doing the right things, but we’re not looking at it through that equity and inclusiveness lens,” she says. “We need to be more forward thinking in who we’re impacting, how we’re impacting them, and being very conscious in disaggregating the populations of students that we have, because they will not all have had the same level of access to high quality educational experiences prior to entering college.”
Cooper encourages professors to do their jobs and actually teach chemistry. “We should be gardeners, not weeders,” she says. “It’s not our job to weed people out.”