A demonstrator wears a sign that reads "Content + expression" during a student rally against the government's public education system in Santiago city Sept 22, 2011. [Photo/Agencies]

A demonstrator wears a mask of Chile's President Sebastian Pinera as he holds a banner that reads "Chilean education is sold" and a Interior Minister Rodrigo Hinzpeter mask during a student rally against the government's public education system in Santiago city Sept 22, 2011. [Photo/Agencies]