Though weeks of negotiations have already passed, it seems like Mayor Rahm Emanuel and the Chicago Teacher's Union cannot come to an agreement. In other words, children had no classes to attend on Monday.

CTU announced on Sunday night, Sept. 9, they were going to strike for the first time in 25 years, according to the Huffington Post. The union's 26,000 teachers and school staff members will protest instead of lead classes until their demands are met.

"In the morning, no CTU members will be inside our schools," CTU President Karen Lewis said Sunday at a press conference. "We will walk the picket lines, we will talk to parents, we ... will demand a fair contract today, we demand a fair contract now."

Lewis noted in her statement that the union was striking over contract negotiations, teacher evaluations and lack of air conditioning in schools, among other issues. Union and school officials have yet to reach an agreement in these areas. The union is also protesting for job security for teachers, compensation and merit pay, according to the International Business Times.

A new evaluation system based on standardized test scores could also result in thousands of teachers losing their jobs, a method that Lewis said was "unacceptable" and "no way to measure the effectiveness of an educator."

The publication reported that the strike currently leaves 700 schools empty of students, with them all at home waiting for an agreement to be set.

"The kids in Chicago belong in the classroom," Chicago Mayor Rahm Emanuel told reporters Sunday night. "Our kids do not deserve this."

The strike leaves around 350,000 students without schools, CNN calculated. However, until negotiations are finalized, churches and organizations in the area have opened their doors to the thousands of youngsters.