It’s something that goes without saying, so obvious that it’s easy to overlook: Every student in the Chicago Public Schools needs to have a good teacher.

A good teacher is the single best thing a school, especially a school in a low-income neighborhood, can provide for children. Research, if anybody needs it, has shown that a good classroom teacher is vital to a child’s academic success.

Sadly, as a recent WBEZ report showed, more than one in four public schools in our city fails to provide this basic need for every child. Last year, hundreds of children — more often than not, African American children in impoverished neighborhoods — were stuck with a parade of substitutes. If that substitute showed up at all, he or she probably did nothing more than hand out a worksheet or show a video.

Editorials

That’s not teaching — it’s babysitting. And things don’t bode well for the upcoming year at some schools.

CPS recently made a pledge to hire more social workers and counselors, especially for schools in troubled neighborhoods. They’re sorely needed, no doubt.

But the district also has to make good on its promises to step up teacher hiring in hard-to-staff schools.

WBEZ’s analysis of data from last school year shows the extent of the problem:

• Citywide, 29% of schools — 152 of 520 — had at least one teacher vacancy that lasted the entire year.

• Schools with low-income and African American students were twice as likely as other schools to have year-long vacancies.

• Schools typically rely on substitutes to fill in the gap. But at dozens of schools, substitutes, who can refuse an assignment, didn’t show up half the time. Once again, low-income black schools had more no-shows.

Savvy students understand the racial and class dynamic that makes their schools, in working-class and impoverished neighborhoods beset by crime, unattractive. Take the case of the Gage Park sophomore whose English class went without a teacher for most of the year.

“We are a high-crime, low-priority school,” Cris Hernandez told WBEZ.

CPS has expanded hiring initiatives like Opportunity Schools, which provides extra recruiting help to schools that have a hard time finding teachers; the program has helped lower the teacher vacancy rate at dozens of schools by 9 percent overall. It’s part of an overall effort to recruit — and retain — new teachers, especially teachers of color and those in shortage areas.

Incremental progress is all well and good. But to make a big leap, think outside the box.

Start with the residency rule that requires teachers to live in the city. In concept, we generally favor residency rules. But CPS already has exceptions for teachers in subjects where there is a severe shortage. Why not for teachers who are willing to commit to schools in tough neighborhoods, like Gage Park? That could have a big impact, especially in mostly black schools on the South Side.

African American teachers who had to quit CPS when they moved to the south suburbs, or who already were living there, might well choose a job in Chicago — which tends to have higher pay — if they could.

Another idea: bonuses for teachers who commit to working in low-income, academically failing schools. North Carolina, for one, tried the idea in the early 2000s, with some success: A modest bonus of $1,800 a year cut turnover among teachers in those schools by 12%.

A big reason for the shortage of teachers across Illinois and the rest of the country is teacher pay. Teachers earn significantly less than professionals in other occupations that require similar levels of education and experience — and their pay is on the decline, as the Center for American Progress, a nonpartisan think tank, points out.

The federal government could start to balance the scales with a $10,000 federal tax credit for teachers in low-income schools, as the center has proposed.

And here’s another idea to chew on: Pay off every new teacher’s college debt if he or she teaches in a high-poverty school for, say, at least five years.

Getting a good teacher for every student, no matter where he or she lives, is worth the cost.

Send letters to letters@suntimes.com.