Thousands of teachers in Mexico City took to the streets to protest again Thursday, as they have for the past two weeks.
And again, they clashed with police and clogged traffic in the famously congested Mexican capital.
The teachers are protesting a new education reform law requiring performance evaluations.
They see it as an attempt to smash the power of labor unions in Mexico.
The government of president Enrique Pena Nieto says it simply wants to fix Mexico's dysfunctional education system.
Reporter Franc Contreras in Mexico City says the new law is clearly designed to weaken the teachers' union, because of abuses such as the right to pass a teaching job on to your children, or to sell it.
But there is also an element of ethnic tension, as many of the protesting teachers work in areas where most kids grow speaking native American languages, not Spanish. The union says these kids need to be tested differently.