While Chicago Public Schools increased arts offerings and teachers overall last year, next month’s threatened layoffs could derail that progress heralded Thursday by one of the city’s arts partners.

An annual report published by the nonprofit Ingenuity Inc. says that about 30,000 more CPS students enjoyed arts education — classes, field trips, after-school activities — in the 2014-15 school year than the year before. The district also hired 44 more arts teachers for a total of 1,322, according to their survey that reached about 85 percent of CPS’ 664 schools. More than half of schools now meet or nearly meet CPS’ arts goals, including 120 minutes of classroom arts in elementary schools or four different courses offered at high schools.

Despite overall gains, about 40 schools still lost some of their arts offerings, mostly on the city’s South and West sides. Most of the schools with weak arts services still abound in those traditionally low-income areas as well. And high schools fared worse than elementary schools.

“You want to see growth in other areas of the city without a doubt,” Ingenuity director Paul Sznewajs said. “And I think what you see on the Near West Side and the South Side is still room for growth, but also a lot of schools turning themselves around.”

Of the 571 schools reporting, 23 still have no arts teacher on staff.

That figure could go up should CPS follow through with February layoffs CEO Forrest Claypool has warned if Springfield doesn’t bail CPS out of a $480 million budget shortfall.

CTU spokeswoman Stephanie Gadlin said that arts teachers are typically cut when CPS reduces staff, and fears that once tax-increment financing funding specifically for arts teachers runs out in June, “then CPS will force principals to treat certified arts instructors just like they have with certified librarians – as expendable.”

CPS spokeswoman Emily Bittner said those layoffs could be averted. The district continues to negotiate with the Chicago Teachers Union on a contract that would prevent them, she said, adding, “We will continue in our efforts to fight for fair funding for Chicago’s students to prevent cuts to our classrooms and arts programs.”

Evan Plummer, the district’s arts education director, said that smaller high schools tend to offer just what’s required for graduation — two courses — rather than the four recommended as ideal under CPS Arts Education Plan.

“There’s no incentive to offer more than two,” he explained. “When you have these smaller high schools that are really concerned with increasing graduation rates, decreasing dropout rates, ensuring that their students are on track, sometimes the interest in increasing the arts may not be seen as one of levers to do that.”

Three years in, Ingenuity still lacks a firm grip on arts offerings in CPS’ 130 charter schools. Some 75 of the publicly funded but privately run schools didn’t respond fully to the survey.

Andrew Broy of the Illinois Network of Charter Schools said there’s no reason to believe those charters have anything to hide.

“I know charters feel inundated by the reporting requirements of CPS and are wary of surveys of all sorts, so the low response rate doesn’t surprise me,” he said. “It is difficult to generalize, but there are quite a few charter schools that either have an arts focus or have varied arts offerings.”

At least a dozen charters earned the top “excelling” rating, including Bronzeville Lighthouse Charter School, which CPS plans to close in June.