Long regarded as the great equalizer, public education holds the potential to enlighten and open doors for every student. But in Hawaii, and elsewhere across the nation, qualified teacher staffing is more equal among some schools than others.

On the first day of the 2016-17 school year, there were 531 teacher vacancies in the islands. The state Department of Education (DOE), which employs some 12,600 teachers and typically recruits 1,100 to 1,200 new hires every year, scrambled to fill the gap with emergency hires — either non-credentialed instructors working toward a teaching degree or substitute teachers. It’s concerning that the scramble is becoming a back-to-school routine.

What’s more, while substitutes are required to hold a bachelor’s degree, exceptions are made for hard-to-staff schools in rural areas such as Nanakuli-Waianae and Hana, on Lanai and Molokai as well as for Hawaiian immersion schools. The upshot is inequality. The overall teaching lineup at hard-to-staff schools is less qualified, with instructors more likely to make a quick exit.

The DOE’s five-year retention rate for teachers hovers at about 50 percent, resulting in a sort of revolving-door that’s not exclusive to Hawaii but exacerbated by mid- Pacific isolation and rookie concerns about how to make an entry-level salary and the high cost of living pencil out.

Also, according to the most recent exit survey for teachers of all tenure lengths, from the 2015-16 school year, “leaving Hawaii” was cited as the top departure reason, accounting for 28 percent of slightly more than 1,200 teachers polled. Retirement, which had historically ranked as No. 1, followed, with 24 percent of responses.

In an effort to put a dent in what educators describe as a perennial problem, the state should redouble its push to produce more homegrown teachers. Our more traditional homegrown programs, both public and private, are churning out some excellent teachers, but at a rate of fewer than 500 a year — filling roughly half the annual vacancies.

So it is heartening to see the DOE now partnering with the University of Hawaii to build local supply with the January launch of the “Grow Our Own” initiative, which will allow some DOE subs and educational aides to earn full teaching credentials at no cost while holding onto their jobs. Moreover, some of their on-the-job duties will fulfill UH field training requirements.

With $400,000 from the Legislature, the initiative offers tuition stipends. In exchange, recipients agree to teach for at least three years in our public schools. Barbara Krieg, the DOE’s assistant superintendent for human resources, has said: “In our discussions and in our data-mining, we realized that we have what we believe to be a built-in demand.” Here’s hoping she’s right.

Last year’s DOE substitute pool included 2,400 instructors with bachelor degree credentials. Securing full teaching credentials would bring better pay and a potentially rewarding career path. Moreover, the pool represents a good bet for stepping up DOE retention rates. After all, these subs already have classroom experience here, and many have deep roots in Hawaii communities.

Among other strategies aimed at increasing local supply is a UH campaign dubbed “Be a hero. Be a teacher,” which targets everyone — from high school seniors and college students to professionals working in other fields and retirees. Indeed, thanks to an abundance of flexible class schedules and online courses, Hawaii can now produce increasingly diverse batches of new teachers.

As it stands at the start of the 2017-18 school year, however, under-qualified teachers and high turnover represent a chronic problem in hard-to-staff schools, with those students being denied a fair shot at an education that approximates the stability and professional depth peers have access to in easier-to-staff areas.

The state must continue to clear unnecessary obstacles from the paths of aspiring teachers, who hold the promise of an improved sense of equality in our public schools.