In deciding on the length of individual periods of observation, it is worth remembering that sytematic recording requires relentless concentration which it is difficult to sustain over a long period. Additional time is needed, of course, for the preparation of record sheets or schedules and for the analysis and evaluation of the information collected. You should decide what your purpose is. While you do not need to be absolutely specific, it is worthwhile writing this down as a series of statements. Focusing the subject You then need to refine your interests and decide what you are going to look at, so as to provide a structure for systematic observation.
Classrooms are busy places, with a lot going on at the same time.
You are then going to have to decide how to break down aspects of the selected behaviour into unambiguous observable, recordable units - see below. While, in some circumstances, there could be advantages in going in cold and not being too specific as to what you are looking at, this is a much more difficult task. The great danger is that the observer will be swamped with items possibly worth recording and, as a result, still be subject to selectivity and form hypotheses which turn out to be atypical. How to record what you see You also need to know how to record what you see. There is nothing more frustrating than finding yourself with a mass of unrelated, incomplete data.