Evidently, charter schools are getting something right.

Between 2006 and 2013, the number of students enrolled in charter schools in San Diego Unified went up by 40 percent, according to the National Alliance for Public Charter Schools, and statewide the number more than doubled.

Add to that, California Charter School Association counts more than 8,000 students waiting to get into charters across the county – 5,080 in San Diego Unified alone.

And yet, we’re still having the same debate today about charter schools that we’ve had for the last 20 years: whether they’re the best way to educate kids, or a threat to public education.

So if charter schools have become increasingly popular, maybe it’s time for us to have a different conversation: One that focuses on where charters excel and whether that success can be replicated.

In San Diego Unified, the school district and charters schools have a kind of frenemy status.

Case in point: The district promised charters a share of a $2.8 billion construction bond that voters passed in 2012, then raised the bar on who can access that money.

And last year, when the school board shot down a charter school that had already been vetted and green-lighted by district staff, trustees reached for reasons to justify the denial: San Diego was already becoming charter school saturated, and too many school closings means the school board should raise the bar on which charters are approved.

That charter appealed to the State Board of Education and eventually won, but it showed how the old tensions can still flare up from time to time.

Some of that tension can be chalked up to simple math: San Diego Unified has a finite number of students, and state funding follows each kid. So the more students who choose to attend charters, the less money for traditional public schools. And some of the brightest students – and teachers – are among those who opt out of their neighborhood schools.

In California and across the country, opponents seize on stories about troubled charter schools and make case that the charter school model is flawed: They’re run like corporations. They have shoddy oversight. They’re gross.

CCSA has tried to keep the pool healthy by creating an accountability framework and advocating for schools’ closures when they’re falling short. Sometimes, though, closing schools still gets messy.

Charters schools in California have made progress in the last several years, especially among students from disadvantaged backgrounds. But in San Diego Unified, charters are still slightly behind traditional public schools, by standardized scores alone.

So if charter school test scores produce mixed results, and on average their scores aren’t any better than traditional public schools, what explains the rise of charter schools?

Flexibility

Charter schools cut across the traditions of public education. Because most charter school teachers in San Diego aren’t unionized, their schools aren’t bound to the same rules.

Last month, The Daily Beast published a list of the top 100 high schools in the U.S., for which it looked at class rigor, graduation and college acceptance rates.

In an accompanying article, it notes that charter schools have an outsize presence on the list.

Much of it comes down to flexibility:

Charters have a chance to build their contracts, schedule, disciplinary systems, and curricula to fit their approach to pedagogy. They can align everything in the school towards making a difference for students, and they can adjust quickly if things aren’t working quite right at the outset.

Indeed, San Diego Unified has recognized the value of flexibility even in non-charters. In July, the district granted schools in La Jolla the ability to shape students’ curriculum or have more say in hiring decisions.

But even with the extra wiggle room, the teachers union would still have to sign off for the changes to happen. So it wouldn’t be the same kind of flexibility charter schools have.

Teaching

We don’t often talk about the teachers who choose charter schools, but charters wouldn’t be growing if there weren’t teachers wanting to work there.

To a certain degree, teachers at traditional public schools can tailor their lessons to their class or school. But compared with charters, theirs is more of a top-down model.

Tom Donahue, executive director of Old Town Academy, told me last year that he doesn’t have any problem recruiting talented teachers.

“Good teachers want to write their own scripts,” he said. That means more freedom to design curriculum and structure classes.

When we walked into his Old Town classroom, Drew Cohick was in front of his computer, recording himself delivering a short lesson. He’d later email the video to his sixth grade math students, so they could watch it at home in advance, and come to class ready to work on the problems.

Cohick structured his classes around a series of lessons, and students didn’t move on to the next lesson until they’d mastered the first. This allowed Cohick to differentiate learning for his students.

Whether it’s a combination of teaching methods, the students who attend Old Town Academy and other factors, something must be going right at that school.

In 2013, 82 percent of the school’s sixth graders scored proficient or advanced on the math portion of California’s standards test. The average for sixth graders districtwide was 58 percent.

An X Factor

About four years ago, Meridith Coady grew so disillusioned with her son’s neighborhood school that her she went looking for other options.

It wasn’t that her son’s school was bad. In fact, it had some of the highest scores in the district. Coady says she felt disconnected from the decisions that impacted her son’s learning.

“It always felt like the tail was wagging the dog. The district was telling the school what to do, but that wasn’t always in the best interest of the school,” she said.

She enrolled both of her kids at San Diego Cooperative Charter School, and hasn’t regretted it. She said the school has a clear vision of what it wants to be, and the governing board, teachers and principal are on the same page.

“With neighborhood schools, I almost feel like the individuality has been taken out of it. There seems to be push to fit our kids into an established, one size fits all template, instead of tailoring classes to them,” she said.

In essence, Coady moved her son from a neighborhood school to a charter because she was looking for an experience – one she felt she couldn’t find at her neighborhood schools.

There are some universals to being a parent. We want our kids to be safe. We want to send them to school and trust teachers will look after them as well as we do.

But other things are harder to measure: like being excited that our kids are excited, enthusiastic about learning. We want them to be engaged, curious, hungry for more – and we want to share in some of that fun along the way.

Clearly, some of that is happening at charter schools. And more parents are seeing these schools as the right fit for their children.

So the charter versus traditional school debate is perhaps a misguided fight. The district is in the midst of a massive push to keep kids in their neighborhood schools, and as it moves forward, it would do well to look at what charters are getting right and find ways to replicate that success.