Randomised, controlled study investigating the optimal instructor: student ratios for teaching suturing skills

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Abstract
Recently, there has been a shift away from practising procedures on patients for the first time and towards bench model teaching of clinical skills to undergraduate medical students. However, guidelines for the most effective instructor : student ratio for technical skills training are unclear. This has important implications for staffing laboratory based teaching sessions. The purpose of this study was to assess the optimal ratio of teachers to learners during the teaching of a simulated wound closure. A total of 108 undergraduate medical students participated in a 1-hour course on wound closure. They were randomised to 3 groups, each with a different instructor:student ratio (Group A: 6-12; Group B: 3-12; Group C: 1-12). Students were evaluated on a pre-test, an immediate post-test and a delayed retention test using an objective, computer-based technical skills assessment method. Collectively termed the "economy of movements", the total time taken to complete the task and the number of movements executed were the primary outcome measures. Improvements in the economy of movements were the same for Groups A and B and were better than in Group C (P < 0.005). The optimal instructor:student ratio was 1 instructor for 4 students. Higher ratios of instructors to students resulted in no improvements in learning, and lower ratios of instructors to students resulted in significantly less learning. These findings are in keeping with current motor learning theories.