In the first week of August, as he was preparing for his 25th year as a middle school social studies teacher, Rob DiPrima got the call CPS teachers have come to fear.

At age 52, DiPrima’s something of a legend at southeast-side Jane Addams Elementary School, where he’s taught seventh- and eighth-grade social studies since 2000.

DiPrima was one of roughly 1,000 CPS employees—including 500 teachers—laid off last month because of budget cuts.

So the project intended to help Addams’s students wound up kicking them in the teeth. So it goes in Chicago.

Generally, union contract seniority rules favor long-standing employees like DiPrima. So in theory a principal should be forced to lay off the last person hired first. But things have changed.

In fact, it’s just the opposite. There’s an incentive for principals to hire the cheapest teachers they can find.