Teachers of the largest school district in Ohio are on strike after failing to agree on a labor contract right before the start of the school year, according to WBNS 10.

The Columbus Education Association (CEA) rejected a proposal from the Columbus City School District in Columbus, Ohio, on Sunday with no future negotiations scheduled, according to WBNS 10. Members of the teachers union protested outside several schools on Monday and plan to picket at 20 everyday this week until an agreement is made.

The union says the school’s proposal did not properly address smaller classroom sizes, higher teacher pay, a school day curriculum that includes physical education, art and music and better facilities including air conditioning and heating systems, according to NBC 4. School is set to start on Wednesday with students learning from substitute teachers.

“Our offer to CEA put children first and prioritized their education and their growth,” Jennifer Adair, president of the Columbus Board of Education, said in a statement. “We offered a generous compensation package for teachers and provisions that would have a positive impact on classrooms. Our offer was also responsive to the concerns that have been raised by CEA during the negotiations process. Our community’s children are the Board’s priority, and our offer reflected that fact.”

About 94% of the union rejected the proposal and voted to strike for the first time since 1975, NBC 4 reported. The strike comes after 22 attempts at negotiation.

“CEA is committed to bargaining for the safe and welcoming, properly maintained, and fully-resourced public schools Columbus students deserve,” the CEA said in a tweet.

The CEA and Columbus City School District did not immediately respond to the Daily Caller News Foundation’s request for comment.