When charter schools move into a neighborhood, people often wonder what will happen to the traditional public schools nearby.
Will they founder? Will they close?
How about ... neither?
According to a new study by Temple University professor Sarah Cordes, traditional public schools in New York City actually improved when a charter school set up shop close by.
And the closer the charter, the better the traditional public schools performed. Schools that shared buildings with charters saw the biggest gains.
Be warned, Cordes said, her study shouldn't be used to justify unchecked charter expansion in other cities.
"I would say mapping this onto Philly probably isn't appropriate for a lot of reasons," she said.
For starters, New York has proportionally fewer charter schools. Only about a 10th of the city's public school students are in charters, compared with about a third of Philadelphia students.
Cordes said the results could look "pretty different" in a city where mass charter migration has caused the public schools in the district to downsize.
"It could be that there gets to be a point where the charter sector is so big it becomes harmful," she said.
New York also has better charter oversight than most cities, she said, and a state funding formula that limits damage to traditional public schools from falling enrollment.
All those caveats stated, Cordes' study does suggest that — at least in limited doses — charter schools can do what many hoped they would when introduced a couple decades ago. Namely, it indicates that charters might, by their mere presence, spark competition and inspire public schools to perform better.