The first step is to identify the most important categories, which, in turn, can be divided into groups. Data can be classified according to these categories, the nature of which will depend on the type of study and the interests at stake. They can refer to the perspectives of a particular problem, to certain activities and events, relationships between people, situations and context, behaviors, etc., for example: when conducting an investigation using this technique, the first thing that was done was to collect the opinions of the whole fourth-year students about school problems that concerned them, while being observed in class and at recess. The first task was to identify what those problems were and to recognize their most important component elements. Thus, the opinions of "students" about teachers were undoubtedly a fundamental problem. It was appropriate to alphabetize the interviews and number the pages. This gave a simple code to identify which part of the material was applicable to which material, and to which aspects of the problem.