A teacher is a person whose professional activity involves the planning, organising and conducting of group activities to develop students’ knowledge, skills and attitudes as stipulated by educational programmes. Teachers may work with students as a whole class, in small groups or one-to-one, inside or outside regular classrooms. In this indicator, teachers are compared by their average age and work experience measured in years. Teachers do not include non-professional personnel who support teachers in providing instruction to students, such as teachers’ aides and other paraprofessional personnel.