Objectives: The objective was to bridge the relative educational gap for newly matched emergency medicine preinterns between Match Day and the start of internship by implementing an Accreditation Council for Graduate Medical Education Milestone (ACGME)-based virtual case curriculum over the social media platform Slack. Methods:We designed a Milestone-based curriculum of 10 emergency department clinical cases and used Slack to implement it. An instructor was appointed for each participating institution to lead the discussion and encourage collaboration among preinterns. Pre-and postcurriculum surveys utilized 20 statements adapted from

Background The COVID-19 pandemic displaced newly matched emergency medicine “pre-interns” from in-person educational experiences at the end of medical school. This called for novel remote teaching modalities. Objective This study assesses effectiveness of a multisite Accreditation Council for Graduate Medical Education (ACGME) sub-competency-based curricular implementation on Slack during the first wave of the COVID-19 pandemic in the United States. Methods Emergency medicine residency programs were recruited via national organization listservs. Programs designated instructors to manage communications and teaching for the senior medical students who had matched to their programs (pre-interns) in spring/summer 2020. Pre- and post-surveys of trainees and instructors assessed perceived preparedness for residency, perceived effectiveness of common virtual educational modalities, and concern for the pandemic's effects on medical education utilizing a Likert scale of 1 (very unconcerned) to 5 (very concerned). Data were analyzed using descriptive statistics and the t test. Results Of 276 possible residency programs, 28 enrolled. Of 324 possible pre-interns, 297 (91.7%) completed pre-surveys in April/May and 249 (76.9%) completed post-surveys in June/July. The median weeks since performing a physical examination was 8 (IQR 7–12), since attending in-person didactics was 10 (IQR 8–15) and of rotation displacement was 4 (IQR 2–6). Perceived preparedness increased both overall and for 14 of 21 ACGME Milestone topics taught. Instructors reported higher mean concern (4.32, 95% CI 4.23–4.41) than pre-interns (2.88, 95% CI 2.74–3.02) regarding the pandemic's negative effects on medical education. Conclusions Pre-interns reported improvements in residency preparedness after participating in this ACGME sub-competency-based curriculum on Slack.