Observation is a form of listening.
How do you use your mental energy after you give an instruction? Are you thinking about the next thing you'll say? Evaluating what you just said? Or are you watching, listening, for how your words land in the students' bodies?
Teaching is like a conversation. We give the cue and then watch to see how it is received and implemented by the students. In the watching is the clue for what should come next, if we can hear it.
Making ourselves available to observe in this way there is connection to each other and to the energy of the moment. Student and teacher meet each other in the presence of yoga.