Leaders at Chicago Public Schools want to close buildings because many have low enrollment.

But a group of parents has released an analysis of state data that throws a curveball into the mix.

How can a school system have too many buildings and not enough students to fill them, as CPS officials say, but at the same time have overcrowded classrooms?

Parents with the Raise Your Hand coalition say three quarters of the city’s elementary schools have at least one grade with average class sizes above what CPS recommends.

“There’s this picture, I think right now, of these half empty classrooms in CPS; obviously if you look at the chart, that’s not the case,” said Raise Your Hand Director Wendy Katten. “Even if you have an empty room in a building, they’re still cramming kids into classrooms because it would cost money. It’s not like they say we’ve got an open room, let’s hire another teacher.”

CPS plans to close and consolidate schools this year based on enrollment. But closings could affect different parts of the city. Chicago Board of Education member Henry Beinen points out that Chicago has “a geographic unevenness, by neighborhood and by area,” in the sense that there are more school-aged children living in certain parts of the city than others.

District spokeswoman Robyn Ziegler said school officials have not seen the report, but noted they’ve “fought to protect class size despite two years of budget deficits, each nearing $700 million.”

Jeanne Marie Olson did the research and analysis on class sizes using state data. She said she started working on the project in August as a concerned parent and did not think about school closings at the time.

“There are a lot of us out there that are not content with just sitting on the sidelines and being the receivers of such an important thing in our children’s lives,” Olson said.

Olson said she hopes the analysis starts a conversation about how CPS calculates school utilization and how it enforces class size limits.