ABSTRACT Purpose Although school-based planned education has steadily been introduced, master-apprentice learning is still an indispensable part of medical education. All medical clinical teachers begin their careers as medical students, often without knowing exactly how they will learn to teach. Kilminster and Jolly identified three primary functions of clinical supervisors including clinical teaching, support and guidance, and work supervision. Therefore, we designed a study using questionnaires to assess the three factors of clinical educators for past supervised experiences, including ‘being instructed,’ ‘being supported,’ and ‘being supervised,’ based on Kilminster and Jolly’s illustration in 2000, to see the relationship between the three factors mentioned above. Materials and Methods The study started with a literature review to construct the essential items regarding past supervised experiences of physicians as clinical teachers. We invited 10 experts from fields including medical education and experienced clinical teachers to assess the content validity. One hundred physicians in teaching hospitals were sampled for the preliminary test. Another 364 physicians in teaching hospitals were sampled for the formal study of confirmatory factor analysis and pathway analysis. Results The” Past Supervised Experiences with Educational Roles Scale” showed satisfying reliability with all Cronbach’s α values exceeding .80, and three factors from supervised experiences were identified, including ‘being supported,’ ‘being instructed,’ and ‘being supervised.’ In our model, the ‘being supported’ experience could positively affect ‘being supervised’ with significance, directly and indirectly, by being instructed. Conclusions Our study developed a validated instrument that allows investigation of the formation of better-supervised experiences from current physicians. Our findings inspired us to focus more on supportive coaching in teaching and supervising medical trainees. Our study indicated that faculty development for skills of supporting students is crucial to effective clinical teaching and supervision.