The acquisition of competence in diagnostic reasoning is essential for medical trainees. Exposure to a variety of patient presentations helps develop the skills of diagnostic reasoning, but reliance on ad hoc clinical encounters is inefficient and does not guarantee timely exposure for all trainees. We present a novel teaching series led by emergency physicians that builds upon the existing medical education literature to teach diagnostic reasoning to preclinical (2nd year) medical students. The series used emergency department simulations involving patient actors and simulated vital signs to provide students with exposure to three acute care presentations: chest pain, abdominal pain, and headache. Emergency physicians coached and provided immediate feedback to the students as they actively worked through diagnostic reasoning. The participating medical students reported benefit from these sessions immediately following the sessions and in an 18-month follow-up survey where the students could consider the impact of the sessions on their clinical clerkship. Students felt that the sessions had assisted them in recognizing the key features of relevant diagnoses during clerkship as well as providing a helpful adjunct to their in-class learning.