Peter, Dave, and Kootvela have given some excellent advice and I would like to conclude by saying that observation - being observed, and observing others at work - is a critical part of a teacher's development. Up until less than a generation or so ago, the courses in teacher training colleges and faculties of education were very heavily focussed on observation by sending their student teachers out to watch others at work. However, a problem lay in the fact that the teachers they were watching were not always demonstrating good examples of teaching.
Since the beginning of the second half of C20, various models of teacher learning have been suggested; the three main ones - as also posited by Wallace (1993) - are:
The craft model: The trainee learns from the example of a "master teacher", whom (s)he observes and imitates. Professional action is seen as a craft, rather like stone-masonry, carpentry, or plumbing, to be learned most effectively through an apprenticeship system and accumulated experience and where the applied science does not necessarily need to be understood. This traditional method is still used in some countries as a substitute for postgraduate teacher development. The downside is that while the master-craftsman to be observed may be a true expert at his job, there is no guarantee that he also knows how to
teach it effectively to others. Watching - also imperative in medicine - is a very slow, passive learning process, and some people may just not be able to acquire some required skills, such as, for example, the enormous degree of dexterity needed for filigree, or for micro-surgery.
The applied science model: The trainee studies theeoretical courses in applied linguistics and other allied subjects, which are then applied to classroom practice. Many university courses are based on this idea. The downside is that on-line and distance TESOL courses can only provide this model, and more and more schools are insisting on TESOL certificates which include an observed, assesed, practical element.
The reflective model: The trainee teacher observes lessons then either reflects alone or in discussion with others, in order to wortk out theories about teaching, then tries these out in practice. Such a cycle aims for continuous improvement (Schön, 1983). This method is used in recently designed teacher training courses. In a well balanced theory-practice syllabus, our experience is that this form of observation and its use works best.
Some excellent advice can be found in:
Classroom Observation Tasks, Ruth Wajnryb 1992, ISBN: 0-521-40722-2
Cambridge University Press
It is mandatory reading in our teacher training courses.