Schools are formal organisations with rules and hierarchies. Researchers may come to be seen as part of the hierarchy. For example, students may see them as teachers, while teachers may see them as inspectors. In schools where there is conflict, for example between students and teachers, researchers may even be seen as 'the enemy'. As well as this, schools are relatively large-scale, complex, highly organised social institutions. They have daily and yearly timetables which may affect when a study can be carried out eg. school holidays and exam periods may severely limit the sociologists research activities.