A citywide education commission is moving forward with a plan to assign A-F letter grades to every school in the city, holding its ground in a battle over who defines what a good school looks like in Michigan.

The Community Education Commission, whose 11 members are appointed by Mayor Mike Duggan, voted unanimously Monday night to dole out letter grades to more than 180 Detroit schools starting in October.

The report cards would lay the groundwork for school improvement efforts in struggling city school systems, argued Tonya Allen, a commission member and president of the Skillman Foundation (a Chalkbeat funder).

“It’s important that the state actually invest in a way to support and improve schools in urban communities — without stigmatizing and shaming them,” she said.

The commission plans to issue grades regardless of what happens with a new state law that calls for every school in the state to get A-F grades in several categories.

That means that Detroit schools could get a host of conflicting grades, forcing Detroit parents, educators and policymakers to figure out whether to believe the new report card from the city — or a different report card from the state.

It might all sound confusing but the two grading systems represent different philosophies about what a good school looks like. It’s a question that could become crucial the next time authorities start making painful decisions, such as whether schools should close or get extra help.

The commission — initially responding to a state law that required a Detroit-only grading system — released a scoring system last fall that would base more than half of a school’s grade on whether student test scores improve or decline from one year to the next.

Commission members said giving lots of points for improvement — a measure known as “growth” — is crucial in Detroit, where many students start school years behind their peers. Growth scores give schools credit for helping students learn even if the students don’t advance enough to produce grade-level test scores.

The commission planned to vote on that grading system in December in time to start issuing grades next fall, but postponed its vote after former Gov. Rick Snyder signed a controversial statewide A-F law during his last days in office.

The law, passed during a lame duck session of the legislature, calls for the state education department to give schools five grades and three rankings in different categories, including one that would be based on growth.

The state education department has objected to the law, saying it could violate federal regulations and cost the state money. The law calls for the state to issue its first grades by Sept. 1, but the department wants to postpone implementation and has asked the Attorney General to review the law’s legality.

The new law also repealed the 2016 measure that called for the Detroit-only grades in the first place, but commission leaders said Monday that they’ve decided to go ahead with their grading system anyway.

“We didn’t give up,” said Stephanie Young, the commission’s executive director. “We still believe in that work. We still believe it would be in the best interest of our students, our families, and we still believe it better represents what’s happening in our schools.”

The grading system the commission approved Monday night is somewhat different from the proposal it released last fall. That’s partly related to the fact that the commission is no longer subject to the 2016 law. The commission’s original proposal had to comply with legal requirements that no longer exist.

Eli Savit, a top education advisor to Mayor Duggan, said the changes make the grading system more compliant with federal law. That way, if the system is successful, the state could consider adopting it for all Michigan schools, he said.

Commission leaders say they’re aware they could be creating additional confusion for families. Even before the letter-grade law, the state was already rating schools using a 100-point scale called an index.

But Savit said he hopes the city’s measurement will cut through the noise.

“Part of the reason we wanted to do this is precisely because there are so many systems out there,” Savit said. “We don’t feel like (the new state law) reflects what makes a good school in Detroit. We think it’s critical that any rating system for Detroit keep the focus on student growth.”

Young, the commission’s director, said the commission plans to do “a great deal of outreach” to spread the word about the commission’s grades and to distribute the commission’s school guide.

She thinks that will give the commission’s grades more reach than existing accountability systems.

Here’s the grading system that was approved Monday night. Called the School Rating System for Detroit or SRSD, it will apply to every school in the city where students take exams. Some schools, including those that only serve students with severe special needs and those that don’t have students in tested grades, will be exempt.

Koby Levin contributed to this report.