Teaching is a highly complex activity. This is in part because teaching is a social practice, that takes place in a specific context (time, place, culture, socio-political-economic situation etc.) and therefore reflects the values of that specific context. Factors that influence what is expected (or required) of teachers include history and tradition, social views about the purpose of education, accepted theories about learning, etc.
The competencies required by a teacher are affected by the different ways in which the role is understood around the world. Broadly, there seem to be four models:
The OECD has argued that it is necessary to develop a shared definition of the skills and knowledge required by teachers, in order to guide teachers' career-long education and professional development. Some evidence-based international discussions have tried to reach such a common understanding. For example, the European Union has identified three broad areas of competences that teachers require: