Advancements in technology have brought about new forms of learning and online instruction that allow communication through virtual representations without physically meeting in person. This study builds on previous work involving recursive feedback that tests the hypothesis that an important facet of learning-by-teaching is the opportunity to watch one's pupil perform. Sixty graduate students examined the value of "recursive feedback" that occurred when tutors observed their pupil subsequently apply what they had been taught. The study took place in the virtual environment Second Life where adults tutored another adult about human biology through their virtual representations. The tutors who observed their pupil avatar interact with an examiner exhibited superior learning relative to several control conditions that included learning-by-teaching elements but not recursive feedback. The second study examined the effect of popular design choices on recursive feedback during learning-by-teaching (e.g., customization, look-alike features). The customization condition involved tutoring a pupil avatar that the participant customized prior to the study and observing the pupil avatar answer questions. The doppelganger look-alike condition involved tutoring a pupil avatar that looked like the participant and observing the pupil avatar answer questions. Results showed that conscious awareness of look-alike features and the extent to which one customizes the pupil avatar influences learning. (Contains 13 figures and 3 tables.)