Medical Students Become Teachers to Sharpen the Art of Clinical Reasoning

Clinical reasoning—the cognitive machinery that lets a physician move from a patient’s scattered complaints to a correct diagnosis and a sensible treatment plan—is arguably the most consequential skill in medicine. It is also one of the hardest to teach. A new program described in the Journal of General Internal Medicine suggests that the solution to this long-standing educational bottleneck may be sitting quietly in the back row of the lecture hall: senior medical students themselves. Researchers at Yale School of Medicine, together with collaborators at the University of California San Francisco and NYU Langone Health, report on a structured peer-teaching role called the Associate Course Educator, or ACE, which embeds senior students as formal, longitudinal leaders in a clinical reasoning course. Over six recruitment cycles spanning 2020 to 2026, the program more than tripled the number of clinical reasoning sessions offered to students and transformed how those sessions were delivered.

The stakes of getting clinical reasoning right are not academic. The National Academies of Sciences, Engineering, and Medicine estimated in its 2015 report Improving Diagnosis in Health Care that most people will experience at least one diagnostic error in their lifetime, a finding that has driven a decade of effort to strengthen reasoning instruction. Subsequent studies have documented the persistence of the problem: research on hospitalized patients under investigation for COVID-19, published in 2023, catalogued the prevalence and causes of diagnostic errors on the wards, and a 2024 analysis in JAMA Internal Medicine found diagnostic errors among hospitalized adults who died or were transferred to intensive care. Cognitive pitfalls—availability bias, premature closure, anchoring on an early hypothesis—are well characterized, and reflective reasoning practices can measurably improve diagnostic accuracy among trainees. The question has never been whether clinical reasoning matters, but how to teach it at scale.

That question is harder than it sounds. National surveys of internal medicine clerkship directors and of clinical skills course directors in the United States have repeatedly shown that clinical reasoning education is uneven, under-resourced, and fragmented across the curriculum. A 2022 cross-disciplinary needs assessment published in PLoS One confirmed persistent gaps in clerkship-year reasoning education, and a 2023 scoping review in Academic Medicine found that preclinical curricula vary widely in content and rigor. A multicenter interview study of European educators published in BMC Medical Education in 2021 asked directly why longitudinal clinical reasoning curricula are so difficult to implement and catalogued the barriers: faculty time, competing curricular demands, and the sheer intensity of the individualized feedback that good reasoning instruction requires. Teaching a student to notice the moment their thinking slips from hypothesis generation to premature commitment demands small groups, careful observation, and conversation—precisely the formats that consume the most instructor hours.

Enter the Associate Course Educator. The program, developed at a private, not-for-profit U.S. medical school, selects senior medical students who have completed their core clerkships and appoints them to a twelve-month term, renewable for eligible students. ACEs are not ad hoc teaching volunteers; they occupy a formal leadership position within the longitudinal clinical reasoning course. Each ACE commits to delivering at least twenty hours of teaching annually, receives close mentorship and explicit instruction in the pedagogy of clinical reasoning, leads educational projects, contributes to scholarship, and participates in curricular review. In other words, the role is designed as a mentored apprenticeship in medical education, not merely an staffing convenience. The Yale Institutional Review Board reviewed the program and determined it did not constitute human subjects research, and all participants engaged voluntarily with consent.

The results, measured across six recruitment cycles, are striking. Eighty-four students applied to the program and forty-four were selected, an acceptance rate of 52.4 percent, indicating substantial demand among students for formal teaching roles. More importantly for the curriculum, the number of annual clinical reasoning sessions grew from eight to twenty-two over the program’s run. Just as telling was the shift in format: sessions migrated from large-group lectures to predominantly small-group and one-on-one teaching—the exact instructor-intensive formats that faculty constraints had made difficult to sustain. By expanding the pool of trained educators, the program changed not just the quantity of reasoning instruction but its fundamental shape, moving it toward the interactive, feedback-rich modalities that education research considers most effective for developing diagnostic skill.

The theoretical foundation for this approach is peer-assisted learning, a well-studied phenomenon in medical education. A 2022 systematic review and meta-analysis in Medical Education examined peer-assisted learning across medical curricula, and a 2025 study in Academic Medicine compared practical skills teaching delivered by near-peers against faculty instruction. Classic work by Olle ten Cate and Steven Durning laid out the psychology of peer teaching, arguing that near-peers occupy a privileged cognitive and social position: they remember recently what it felt like not to know, they speak the learner’s language, and the social distance between teacher and learner is small enough that students ask questions they might hesitate to raise with faculty. Teaching itself also consolidates the teacher’s knowledge—a principle long recognized in students-as-teachers programs, which a 2010 national survey in Academic Medicine found had proliferated across U.S. medical schools even before programs like ACE formalized them into leadership roles.

What distinguishes the ACE model from a conventional teaching assistantship is its explicit pairing of peer teaching with leadership and scholarship. ACEs did not simply staff existing sessions; they generated educational innovations that the authors report contributed to the institutional curriculum, and they disseminated their work at regional and national academic venues. The program’s appendix catalogs notable projects in undergraduate medical education produced by ACEs during their terms. This design reflects a growing conviction in medical education research that future clinician-educators need early, structured exposure to the craft of teaching. Studies of clinician educator tracks during internal medicine residency have found that longitudinal education curricula shape participants’ trajectories and skills, and a 2025 modified Delphi study in Academic Medicine reached consensus on the most important teaching skills for residents in clinician educator tracks—skills that programs like ACE begin cultivating years earlier.

The timing of this innovation is significant for another reason. Clinical reasoning is increasingly framed not as an implicit byproduct of clinical exposure but as a core competency in its own right, with published consensus statements defining the content of undergraduate reasoning curricula and interprofessional frameworks specifying the competencies needed to improve diagnosis. Educators have developed a toolkit of teaching and assessment methods—script concordance testing, serial concept maps, the clinical integrative puzzle, the Assessment of Reasoning Tool—each designed to make the invisible process of diagnostic thinking visible and gradable. Recent work has extended the framework beyond diagnosis to management reasoning. Yet all of these methods share a common requirement: trained facilitators who can model reasoning aloud, probe a learner’s differential diagnosis, and deliver calibrated feedback. A program that multiplies the number of such facilitators, at modest cost, addresses the central constraint on every one of these methods.

There are, of course, open questions. The published report is a program description and evaluation rather than a controlled trial, and the authors themselves sit within a broader conversation—reflected in a 2026 JAMA Internal Medicine commentary—calling for more experimental studies in medical education. Whether ACE-taught students show measurable gains in diagnostic accuracy compared with traditionally taught peers remains to be tested, as does the durability of benefits for the ACEs themselves as they progress to residency. But the program’s six-year track record demonstrates proof of concept: a formal, longitudinal, leadership role for senior students can expand instructional capacity nearly threefold, sustain the small-group formats that reasoning education demands, and simultaneously build a pipeline of future clinician-educators. At a moment when diagnostic error remains a leading patient safety concern and faculty teaching resources are stretched thin, the idea that the most scalable new educators in academic medicine might be the students one year ahead is an audacious one—and one that other institutions are likely to watch closely.

The deeper lesson of the ACE experiment may be institutional rather than cognitive. Medical schools have long treated teaching as something faculty do and students receive, with students-as-teachers programs occupying a peripheral, often extracurricular niche. By converting peer teaching into a structured leadership position with mentorship, curricular authority, and scholarly expectations, the ACE role argues that learners can be genuine partners in building the curriculum—especially for a skill like clinical reasoning, where the recent learner’s perspective is itself a teaching asset. With forty-four selected educators, twenty-two annual sessions, and scholarship reaching national audiences, the program offers a template that requires no new faculty hires, no expensive simulation equipment, and no curricular revolution—only a willingness to reconceive who, exactly, is qualified to teach the art of thinking like a doctor.

Subject of Research: A peer-assisted learning program using senior medical students as formal educators to strengthen clinical reasoning instruction

Article Title: The ACEs of Clinical Reasoning: a Formal, Longitudinal, Leadership Role for Medical Students to Augment Clinical Reasoning Education

Article References: Tang, Z., Swallow, M. A., Bahar, R. C., Gaeta Gazzola, M., & Wijesekera, T. P. (2026). The ACEs of Clinical Reasoning: a Formal, Longitudinal, Leadership Role for Medical Students to Augment Clinical Reasoning Education. Journal of General Internal Medicine. https://doi.org/10.1007/s11606-026-10904-7

Image Credits: AI Generated

DOI: 10.1007/s11606-026-10904-7

Keywords: clinical reasoning, medical education, peer-assisted learning, near-peer teaching, diagnostic error, medical students, curriculum design, clinician educators, feedback, Yale School of Medicine, Journal of General Internal Medicine, ACEs