Students protest in front of and on the roof of a riot police vehicle, which has been vandalised with paint, during an anti-government rally to demand changes in the public state education system in Valparaiso city, about 121 km (75 miles) northwest of Santiago, August 4, 2011. REUTERS/Ivan Contreras (CHILE – Tags: EDUCATION POLITICS CIVIL UNREST IMAGES OF THE DAY)
