Teachers pick up picketing signs and other materials from the Chicago Teachers Union strike headquarters on the morning of Sept.10, 2012. Talks broke down on the final day of negotiations between the CTU and the district, sparking the city's first teachers strike in 25 years. Photo by Jonathan Gibby.

It’s official: the Chicago Teachers Union is on strike.

That was clear Monday morning when clusters of teachers, parents and students held signs while marching in front of schools. At some schools, they were chanting for what they called a fair contract. The cars that whizzed reflected the varying opinions Chicagoans have about the strike. Most cars blared their horns in support, there were a couple of thumbs down and even the occasional middle finger.

[Photos by Jonathan Gibby and Lucio Villa]