Wikipedia
Micro-teaching is a teacher training and faculty development technique whereby the teacher reviews a recording of a teaching session, in order to get constructive feedback from peers and/or students about what has worked and what improvements can be made to their teaching technique. Micro-teaching was invented in the mid-1960s at Stanford University by Dr. Dwight W. Allen, and has subsequently been used to develop educators in all forms of education.
In the original process, a teacher was asked to prepare a short lesson (usually 20 minutes) for a small group of learners who may not have been their own students. This was then recorded on video. After the lesson, the teacher, teaching colleagues, a master teacher and the students together viewed the videotape and commented on what they saw happening, referencing the teacher's learning objectives. Seeing the video and getting comments from colleagues and students provided teachers with an often intense "under the microscope" view of their teaching.
A review of the evidence for micro-teaching, undertaken by John Hattie as part of his Visible Learning project, found it was an effective method for improving student outcomes.