The Gulen movement, which the Turkish government has declared a terrorist organisation, runs schools all over the world.
Since July's failed coup, Turkey has cracked down any individuals or groups on believed to have links to Fethullah Gulen.
Tens of thousands of people from every of society have been purged from their jobs, senior military officers, government officials and school teachers.
Critics of President Erdogan say he has used the coup attempt as a way of removing his opponents.