With all our figuring out, it was time to return to the situation that started this all--the teacher being able to see the student in his music room, while he could only see himself! Students worked in groups to explain the phenomenon, then offered feedback to each other on what was evident and clearly explained vs. what needed clarity/removing!
With lots of critical thinking involved, we settled on the following:
Next steps: Recognizing that there are times where we have multiple inputs of light entering our eyes, like when the teacher not only sees the student clearly, but also a slight reflection of herself! How do our eyes work to interpret both of these inputs?