Data, therefore, can play an important role in the coaching cycle of planning - observation and reflecting. During a planning conversation, a coach will first ask questions to clarify a teacher's goals and what success looks like. At this point the idea of conducting an observation to collect data could be a useful discussion so that the teacher will have evidence of success. The important thing here is that the coach and teacher need to agree together on what data to collect, and when and how to collect it. It's really important that the teacher being coached agrees on this, otherwise an observation can very easily be seen as an evaluation. The coach therefore needs to ask the teacher what s/he wants to have observed and recorded and what tools would be most useful for subsequent reflection (for example perhaps the teacher wants the coach to scribe all the questions being asked, or to count the amount of wait time or to use tally marks to count how often a certain behaviour is happening among students).
Following the observation, during the reflecting conversation the coach then needs to communicate the data in such as way as to promote the self-directedness of the teacher. First the person being coached needs to think about what s/he can recall of the lesson, and only after this self-reflection should the coach share the actual data so that the teacher can see whether the data supports their initial impressions about the lesson. Often, if there is a discrepancy, the data can be useful as the "3rd point" in the conversation, as it can depersonalize a contentious issue and prevent a teacher becoming defensive. In this situation a coach simply needs to share the data and ask "What patterns do you notice?" The coach's role at this point is to ask mediative questions as this is where the new learning for the teacher happens.
Effective teachers are themselves lifelong learners. By asking mediative questions to help a teacher analyze, interpret and draw conclusions based on the data collected during their classroom observations, a coach can help a teacher to explore ways they can modify their actions as they work towards achieving their goals.