You can find plenty of microteaching videos on Youtube to get an idea of this method (example). Technical aspects are less important than the later analysis which allows teachers to get a microscope-view on your own teaching. Under the guidance of a supervisor, the student-teacher is first asked to present a self feed back of his mini lesson, then the team gives feedback to provide positive reinforcement and constructive criticism.
Examples for micro-teaching: Since its invention in the 1960s at Stanford University by Dr. Dwight Allen, microteaching has become an established teacher-training procedure in many universities and school districts. You can find more information on micro-teaching here or here.
Micro-teaching offers the opportunity to present an instance of what or how you teach and to get feedback from other teachers about how your teaching is received.
It can also be used as a chance to try new teaching strategies in a safe non-judgemental laboratory environment.
The goal of micro-teaching is to give you confidence, support and feedback so you can improve your teaching methods.