When Norma Sandoval was a second-year teacher in the 1990s, this is how she thought of herself: “I’m a great teacher. I’m gonna save the world, just with all the love I have for my students.”
She now realizes her hopefulness was overblown – and so was her estimation of her skills. “Year two, I’m really in survival mode,” she said recently, thinking back to that time. “I’m still trying to make sense of what I’m going to be teaching.”
Year-over-year, the changes in her abilities were dramatic, said Sandoval, who is now the principal of the charter school McGill School of Success. “By the ninth year, you’re a sage, who gives advice. You’re a guide.”
Research backs up Sandoval’s assessment. Studies have shown that teachers tend to gain measurable effectiveness even into their third decade of teaching .
Sandoval works at a charter school, which has valued such expertise. Teachers, on average, have more years of experience at McGill than any other charter school within San Diego Unified School District.
But on the whole, charter students in San Diego Unified do not benefit from experienced teachers nearly as much as their peers. Teachers within San Diego Unified’s traditional public schools have twice as much experience, on average, as their charter school peers, according to an analysis of Department of Education staffing data by Voice of San Diego and the UC San Diego Extension Center for Research and Evaluation.
The average charter school teacher within San Diego Unified has 7.8 years of experience. The average traditional school teacher has 16.5 years, according to the analysis.
“Some people think once you have been a teacher two or three years, you plateau and after that it doesn’t matter. They won’t improve over time. But, on average, teachers do improve over time,” said Anne Podolsky, an analyst at the Learning Policy Institute, a nonprofit research center devoted to education.
Podolsky and Tara Kini of Learning Policy Institute reviewed 30 different studies on teacher experience in 2016 and found that effectiveness, as measured by test scores, continues to grow through the decades . They found that a teacher with 12 years of experience was able to provide the equivalent of three additional weeks of learning in a single school year in English and seven additional weeks of math, compared with a teacher with no experience.
They found that a teacher with 27 years’ experience was able to provide the equivalent of an additional two and a half months of learning in a school year, Podolsky said.
While teachers definitely grow over time, Podolsky cautioned that a random 10-year teacher can’t easily be compared against a random second-year teacher. In some cases, the second-year teacher might be better. Maybe she had more training or more access to professional development. What is nearly certain is that both teachers will grow over time.
E3 Civic High School ranked near the bottom for average teacher experience among San Diego charter schools. But E3’s principal Cheryl Ward said that is likely because the school itself is just entering its seventh year.
“I think if you checked back in 15 years, you’d find many of the same teachers at E3 and our years of experience would be on par with others,” she wrote in an email.
She also noted that the staff is diverse in age, ethnicity and background. E3 spends “a great deal of time coaching both new and experienced teachers,” Ward wrote.
Other schools have been around much longer and have even lower average years of teacher experience, including several schools within the High Tech charter schools. High Tech High International, High Tech High Media Arts and High Tech Middle Media Arts are among the four lowest-ranked schools for teacher experience, and were all opened in 2005 or earlier.
High Tech’s chief executive officer Larry Rosenstock did not respond to a request for comment.
If a school has been open relatively longer, but has very low average years of experience, it suggests teachers may not be staying at the school for long periods of time.
Higher rates of teacher turnover are associated with poorer outcomes for students, Podolsky said.
Teachers in their first three to five years of experience make the steepest gains in effectiveness, she said. That means teachers in the very earliest years of their careers are operating at the low-end of their potential.
At High Tech Elementary, opened in 2015, the average teacher has just 2.2 years of experience.
A recent study from the U.S. Department of Education showed that charter schools, on the whole, are not likely to measurably improve a student’s chances of success  compared to traditional district schools.
Some individual charter schools, however, such as The Preuss School in San Diego, have seriously outperformed many district schools with comparable demographics.
Veteran teachers tend to cost schools more money, and most charter school teachers do not have tenure protection, whereas teachers in traditional public schools secure significant protections after two years on the job. That means many charter schools have more freedom than district schools to fire teachers who they don’t believe are performing well – or those they believe are costing too much money.
Preuss teachers unionized in 2017 . But their contract did not include a provision for tenure.
Sandoval, the principal at McGill, acknowledged there was a push at some point in the school’s history to do away with some of the more senior teachers. In the end, too many people wanted the veteran teachers to stay, she said. At least one teacher has been around almost since the school’s founding in 1996, Sandoval said. A couple of others have been at the school more than a decade.
“If we were just to be driven by saving money and let go of people, it would take away the essence of what McGill is,” she said. “That’s not us. We’re not about a revolving door of people.”