We told you so.

Parents, community activists, teachers, education experts and this editorial page all warned City Hall back in 2013 that closing dozens of schools in one fell swoop was a bad idea.

And if Mayor Rahm Emanuel still didn’t get it, plenty of research sounded the same warning: School closings can really set kids back, academically and socially.

So the neon signs were all flashing “STOP” when Emanuel and Barbara Byrd-Bennett, who was the CEO of the public schools, decided to close 50 elementary schools on just three-months’ notice.

EDITORIAL

We were not opposed to school closings in general, nor were most other skeptics; sometimes an under-enrolled and poorly performing school just has to be shut down. We also never doubted Emanuel’s good intentions, though others did. This was a mayor who sincerely believed he had to go bold, moving hard and fast, to make the school district more financially efficient and — he felt certain — boost the quality of education.

And he wanted it all behind him well before the next election.

But Emanuel could have listened a little more. He could have taken to heart the advice of those who urged him to slow down, close fewer schools over a longer period of time, and do much more planning beforehand.

Because uprooting 11,000 kids over a summer was just too much, too soon.

We’re not surprised, sad to say, that University of Chicago researchers have confirmed those predictions. The closings, a new report has found, fell far short of the mayor’s pledge to give kids stuck in failing, under-enrolled, schools a “brighter future” elsewhere.

The Consortium on School Research study — the most definitive study yet, on the largest mass school closing in the country — found ample evidence that can’t be denied.

Textbooks and other materials were lost during the transition. Some of the welcoming schools weren’t cleaned and rehabbed before the new school year. Tension and conflict cropped up as schools tried to bring together the displaced children with existing students.

On average, the children who were uprooted — most of them low-income, African-American kids — did worse academically after the closings.

And let’s not overlook another lousy outcome: Some of the closed school buildings are still, five years later, vacant or unsold. People in the affected communities, which already had a glut of boarded-up buildings, warned the city about that, too.

The study concludes that closing large numbers of schools quickly might seem smart and responsible, but if we’re talking about really helping kids, it’s not. And, by the way, we’re still waiting on solid figures to prove that there was a financial savings.

So now what?

The district can’t undo the damage. But it can avoid repeating past mistakes. That’s crucial, given that more schools are slated to close, and even more will have to be closed if CPS enrollment continues to decline.

Above all, for heaven’s sake, City Hall had better make sure that any child displaced by a school closing lands in a better school.

CEO Janice Jackson has promised to heed the lessons of past mistakes, and that’s nice to hear. The district now, for example, will phase out four under-enrolled high schools in Englewood, rather than closing them all at once.

But here’s another suggestion: If the Chicago Public Schools really believe in “school choice,” CPS should give future displaced kids the pick of any other school, bar none — including selective and charter schools.

Don’t let test scores or application deadlines be a barrier. Make it happen. Embrace the research that shows that putting students in an academically challenging environment can motivate them to rise to the occasion.

Let’s put kids before politics every time.

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