Editor’s note: This editorial has been updated to reflect new facts provided by the Chicago Public Schools.

Lots of Chicago teachers call in sick when they are not sick.

Just because they can.

Yes, we’re talking about those very same members of the Chicago Teachers Union who just staged a two-week strike to fight — so they told us time and again — for Chicago’s kids.

As reported by Matthew Hendrickson of the Sun-Times, that sad fact lies behind a little noticed provision in the teachers’ new tentative contract. The teachers will be allowed to accumulate as many as 244 sick days, which they can put toward an earlier retirement with a full pension. Some teachers will be able to retire about a year and half early.

Editorials

Why would Mayor Lori Lightfoot, the Chicago Public Schools and CTU agree to this change in the contract?

To give teachers who are not sick a greater incentive not to call in sick, which is among the more inexcusably disruptive things that can happen to a classroom.

CPS found that teachers have been calling in sick about 27% more often since 2012, which is when a provision was eliminated that allowed teachers to save up and cash in — for hard money — up to 325 unused sick days when they retire.

An earlier version of this editorial reported that, according to CPS, teachers have been calling in 150% more often. CPS has since notified us that this higher percentage was “accidentally miscalculated.”

CPS also, however, has provided additional information that underscores the problem is nonetheless very real. Since 2011, CPS has seen a 58% increase in “teacher absences” — sick days, personal business days and religious holidays. That works out to 3.5 additional days off per teacher, from 6 days to 9.5.

For a discussion of that CPS error, and our unwitting part in passing it on, please read this Sunday’s editorial.

The teachers’ excessive use of sick days has created a problem for Chicago’s public schools at a time when it’s increasingly difficult to line up substitute teachers, given competition from the gig economy. And even the best substitute teachers can’t make up for the loss of continuity in learning.

Chicago’s schoolchildren have paid the price.

Editorials

It’s unfortunate that things ever got to this point. It’s regrettable that teachers apparently need a little more incentive to call in sick only when they are genuinely under the weather.

That was the thinking during contract negotiations in 2012 when, to save the school district tens of millions of dollars, the 325 unused sick days a teacher could cash out at retirement was eliminated. The assumption then was that the vast majority of teachers, being committed professionals, still would call in sick only when they truly were ailing.

And maybe they did, right? Maybe it’s just a stunning coincidence that teachers instantly began to catch so many more colds and fevers and had to call in sick 27% more often.

In any event, both sides in this year’s contract talks apparently agreed that a use-it-or-lose-it approach to sick days is not in the best interest of the kids.

The financial impact of this change in the teachers’ contract is hard to estimate. There will be some increase in pension liability costs for CPS, as teachers retire slightly earlier than they might have.

CPS also will realize a savings as highly paid longtime teachers retire a little earlier and are replaced by more modestly paid new hires.

CPS’ new system for banking sick days aligns more closely with that for downstate and suburban teachers, who are allowed to accumulate up to two years of unpaid sick leave. The teachers can add those sick days to their years of service, boosting their pensions.

Chicago’s new rule — teachers can bank up to 244 unused sick days for an earlier retirement — makes good sense, but the need for such a rule is pathetic.

Send letters to letters@suntimes.com.