Chicago teachers remained on strike Monday, freezing 300,000 students out of crucial instructional time. Why? The reasons are growing, but they aren’t about pay or working conditions.

The latest reason: President Donald Trump visited Chicago to speak to police chiefs before heading to a ritzy fundraiser hosted by Chicago Cubs co-owner Todd Ricketts. No way could Chicago Teachers Union leaders miss out on the opportunity to protest Trump and a 1-percenter, together, on the same day. That was a double aphrodisiac the socialist-leaning CTU could not deny itself.

Unable to reach a contract agreement over the weekend — insert skeptical eye roll — union leaders sent a note to teachers early Monday encouraging them to protest Trump’s visit wearing their red T-shirts.

“After pickets Monday, the CTU has not planned any afternoon activity. Feel free to rest or take part in any productive activity of your choosing. We have heard that President Trump might be in town. If any members were inclined to show up outside his fundraiser in red, that would qualify as productive, in our view,” CTU leadership wrote.

It’s not surprising but interesting, given that Trump’s Department of Education under Secretary Betsy DeVos deserves praise for stepping in to oversee Chicago Public Schools’ handling of sex abuse and assault allegations. CPS failed miserably to protect students, an exhaustive Chicago Tribune investigation last year showed. From 2008 through 2017, police investigated more than 500 cases of reported sexual abuse or assault inside a city school. But most of the cases got swept under the rug.

When a consultant and former federal prosecutor hired by the district tried to interview CTU President Jesse Sharkey as part of a broad examination into school policy and how to improve it, he did not participate:

“The Chicago Teachers Union President is the only person we contacted who failed to respond to our inquiries. We made multiple attempts to contact him by phone, by email, and through his assistant and office, during both our preliminary and follow-up evaluations,” the investigator wrote.

A CTU spokeswoman said the emailed invitations must have gotten lost in a spam folder.

Meanwhile, DeVos’ department embarked on an oversight plan to reverse CPS’ failures, which “were widespread, glaring and heartbreaking. Too many innocent students suffered because adults didn’t do their jobs,” DeVos wrote in September. Her department, alongside a reformed CPS, is doing more to hold sexual abusers in schools accountable. Sharkey wouldn’t even sit down for an interview.

Teachers have had a generous contract offer on the table for weeks, plus a commitment in writing and funding set aside for nurses and social workers in every school, which supposedly were the reasons they walked out in the first place. So why are they still striking? It’s rhetorical. You know why. The union was never not going to strike.

CTU leaders who backed Chicago Mayor Lori Lightfoot’s rival in the last election certainly weren’t going to hand Lightfoot a victory for avoiding a strike. And union members weren’t going to strike for just a few days, not after getting the strike factory humming — the signs, the T-shirts, the team-building, the solidarity. It’s good business for CTU.

Employees no longer are required to join a union and pay dues, following the U.S. Supreme Court’s 2017 Janus decision. That ruling determined that workers could not be forced to pay even nonpolitical fees to a union without violating their First Amendment rights.

The decision has diminished the budgets of employee unions across the country, according to an April analysis by the Competitive Enterprise Institute, a free-market think tank. Union membership hasn’t plummeted. But nonmember employees who were paying only “fair share” dues in states that required it quit paying altogether.

The National Education Association, for example, the nation’s largest teachers union, lost payments from 87,000 workers following the Janus ruling, the study found.

So strikes have become team-building exercises for teacher unions that are trying to stay relevant. Strikes galvanize. They motivate. They bond. It’s an exercise CTU doesn’t want to cut short.

See how the strike is all about the kids, Chicago? Your vision should be crystal clear.