For families with students under 18, studying in pre-university, TAFE or university
Under Australian Government regulations, students under 18 must have an approved guardian.This is a compulsory requirement for obtaining a student visa, for a student under 18 years
Department of Immigration - Student Visa requirements (click to view requirements)

Guardianship for Younger Students

Younger students (under the age of 16 years or at High School) need more supervision, care and support, for details see High School Guardianship