Here are some suggestions to help navigate this situation:
Create a checklist with your teaching partner about what you
expect to see.
Ask you teaching partner what you would like to him/her to focus
on during the observation.
Focus on one area for improvement (chosen by the teacher being
observed)
In writing class, we use TAG - Tell the person all the success
criteria they met, Ask a question about one criterion not met,
Generate ideas together. This could be used in your situation:
After collaboratively creating a criteria list, tell your
teaching partner what criteria were met, ask a question about one
that wasn't met (Such as What are some ways that you could adjust
the pacing of the lesson?) and then, as a team, generate ideas
that both of you could use to improve your practice.
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