The purpose of this study was to determine how students, teachers, and outside observers perceive teaching effectiveness within a university-level string ensemble rehearsal setting. Students, teachers, and observers reflected on six rehearsal segments that used primarily nonverbal, co-verbal, or verbal instruction as outlined by Bob Culver in the "Master Teacher Profile." Overall, participants viewed the verbal teaching episodes as being most effective, and expressed a preference for several elements associated with the verbal instructional mode. Five common elements of effective rehearsals identified by participants were Specific Instructions and Feedback, Delivery Skills and Eye Contact, Audible and Focused Co-Verbal Instruction Prompts, Conducting Effectiveness, and Ensemble Progress. Effectiveness perceptions were colored by participants' sense of each teacher's comfort with the different instructional modes as well as the elements of rehearsal teaching they personally valued.