School principals are the link between teachers, students and their parents or guardians, the education system and the wider community. Principals may contribute to student achievement through their impact on how the school is organised, the climate in the school and, especially, teachers and teaching. They can set the tone for teachers by encouraging new teaching practices and improvement of teachers' skills and by ensuring that teachers feel responsible for students’ learning. These practices are part of what is known as instructional leadership. In this indicator principals are compared by average age and work experience, measured in years and broken down by gender.