Protesting teachers light a bonfire in Mexico City main plaza, the Zocalo, Friday, Sept. 13, 2013. Thousands of teachers who have camped out at the Zocalo for more than a month have been told by authorities they need to leave today setting the stage for what could be an ugly confrontation culminating weeks of protests against an education reform. As federal police helicopters swooped low overhead Friday, teachers struck tents they have been living in for weeks and burned garbage and plastic traffic barriers, filling the Zocalo with thick, acrid smoke. (AP Photo/Eduardo Verdugo)