The offer applied to elementary school teachers. Brizard wanted to extend the school day beginning in January.
Brizard and Mayor Rahm Emanuel want to add an extra 90 minutes to the school day and an additional two weeks to the school year.
Emanuel held a back to school breakfast Thursday with 400 religious leaders at US Cellular Field. Emanuel asked them to sign petitions showing their support for his proposal and to spread the word among their congregations.
"They're all our children," Emanuel said. "They're the children we are accountable for. And the children of the City of Chicago have the shortest school day and the shortest school year of any major city in the country."
Brizard said that he was disappointed that the teachers union rejected his offer.
Union president Karen Lewis said teachers would have been working 29 percent longer for just a 2 percent raise.