It is the first such strike by charter school teachers in U.S. history.
About 500 teachers and staff members at the 15 charter schools walked out Tuesday after failing to reach a new contract. After seven months, negotiations broke down shortly after midnight.
The closings affect 7,500 students.
RELATED: Acero teachers become first charter school educators in US history to go on strike
Acero schools CEO Richard Rodriguez posted a YouTube video after the bargaining was over expressing his disappointment in the decision.
"The sad fact is that interests from outside our community are using our students and our schools as a means to advance their national anti-charter school platform," Rodriguez said. "They don't want our schools to succeed because it doesn't serve their agenda."
But teachers and staff at Acero said some of the critical issues they are fighting over include class sizes, an increase in special education staff and greater compensation.
"He completely disrespects the teachers that he would think these teachers could be used by anybody," said Randi Weingarten, president of the American Federation of Teachers. "They are fighting for their kids and themselves and they have the vehicle of a union to do that."
While the Chicago Teachers Union is strongly against the expansion of charter schools, Acero teachers joined the CTU a few years ago. Acero teachers said they are fighting for equal compensation to their CPS counterparts, as the pay disparity causes a high teacher turnover rate.
Because more than 90 percent of Acero students are Latino, teachers are asking that all 15 schools be declared sanctuary schools, and that no information is shared with ICE and no one is let inside the schools without a warrant.
Rodriguez said Acero schools have prepared for this strike and are keeping parents informed, and are offering resources for parents to drop off their kids. Acero officials say they will remain at the negotiating table.
For a full statement by Acero, click here.
For a statement by the Chicago Teachers Union, click here.