Arizona now tops the list of states with the most crowded public school classrooms, with an average of 22.7 students per teacher — nearly double the average in the state’s private schools.
That 45% gap, one of the widest in the nation, raises questions about equity, access and long-term student outcomes.
A tale of two school systems
Arizona’s public schools serve students at a ratio far above the national public school average of 15.4 students per teacher, according to the latest data from the National Center for Education Statistics. Meanwhile, private schools in the state average just 12.4 students per teacher, reflecting a system where smaller class sizes often are a function of tuition, geography and privilege — not policy.
Arizona isn’t alone. California, Massachusetts and Alaska also show large disparities in public versus private class sizes, but Arizona’s gap is particularly stark given its sustained teacher shortages, low funding for education and a student population that is decreasing in public schools while experiencing growth in private schools and homeschooling.
"I once taught in a district high school that had 35 seats and 37 students on the roster," said Jim Buckley, a retired Arizona teacher. "The seating chart was based on who was late and who was absent any given day."
Karie Pesserillo, a teacher at AMS Camelback, agreed. “In 2022–23, I taught sixth grade and had 38 students. The more students, the less space in the classroom for movement and to pull a small group.”
Not all educators agree
Not all teachers or administrators agree on the optimum class size.
"I've been in classrooms all around the state and I've learned that you'll have a great school if you have a great leader," said Margaret Garcia Dugan, deputy superintendent of the Department of Education. "You can't blame on the teachers or the kids if the administrator isn't on board. Administrators need to be on campus to know what's going on at the school."
According to Dugan, the optimal class size depends largely on the subject matter, grade level, teacher experience and the effectiveness of the administrator.
"Small is not always better. When you lower class size to 15, some students don't come to school on regular basis. This increases absenteeism and can result in classes that are too personal," she said.
What’s behind the crowding?
Education experts point to three primary causes: teacher attrition, underfunding and policy inertia.
Teacher shortages have plagued Arizona for years. In the 2023–24 school year, more than 30% of teacher vacancies went unfilled, and 53% were staffed by individuals who did not meet standard certification requirements, according to the Arizona School Personnel Administrators Association.
As the ESA voucher fund grows in popularity, officials say they expect to see many public education teachers fleeing from public schools to teach at better-funded, smaller schools where class size and work load is dramatically lower.
Funding shortfalls are structural. Arizona ranks 48th nationally in per-pupil funding, investing about $9,200 per student in 2024 compared with the national average of $14,300. Arizona's ESA program spends roughly $9,000 to $10,000 per student (significantly below the $14,000-plus benchmark for public-school peers), but shifts existing funds, which lowers public school per-pupil spending and constrains budgets statewide.
State policy has failed to cap class sizes, and many schools have had to increase teacher loads to offset budget constraints. A 2023 audit by the Arizona Auditor General found that 47 school districts were at high risk of exceeding their budgets, many due to payroll shortfalls and insufficient capital allocations.
As of Dec. 21, 2023, 47 of Arizona’s 207 school districts were identified as "high risk" of exceeding their budgets. This is largely due to low operating budget reserves and redirected capital funds. The audit explicitly warned that these districts have been using capital improvement dollars to shore up basic operational costs, including payroll, which has created structural budget pressures.
Why class size matters
While some argue class size is just one variable in a complex system, a large body of research supports its importance — especially for younger students, special education, low-income children and students of color.
“A cap of 15 students would be better,” said Wendi Miller, 9-12 SpEd Teacher, Public Charter Title I. “But, an ideal size would be 12 students with a teacher assistant for special education classes.”
“I worked at two different charter schools,” said Denise Vann, a retired Phoenix teacher. “One with 28 kindergartners and no aide. The other had 20 students max and two aides. The ideal class is smaller with more subjects.”
The Tennessee Student-Teacher Achievement Ratio study, or STAR, remains the landmark study for class size. It found students in smaller classes (13 to 17 students) outperformed those in regular-sized classes (22 to 25 students) in both math and reading.
Notably, the gains were more pronounced for Black students and students from economically disadvantaged households. These students were also more likely to graduate high school and attend college.
Follow-up studies from the National Bureau of Economic Research and the Brookings Institution confirm that benefits of smaller class sizes include:
Private vs. public: The equity divide
Private schools’ smaller class sizes are often marketed as a major advantage, appealing to parents who want more individualized attention for their children.
But in Arizona, where 94% of students attend public schools, the benefits of reduced student-to-teacher ratios are largely limited to a small, more affluent segment of the population. This creates a widening opportunity gap: students in wealthier households gain access to smaller, quieter classrooms while their public school peers face growing class sizes, limited support staff and fewer academic resources.
As a result, access to a high-quality education is increasingly determined by a family’s ZIP code or income level — undermining the promise of equal opportunity that public education is meant to provide.
What’s being done?
“All of this comes back to state funding," said AEA President Marisol Garcia, a middle-school social studies teacher in the Isaac School District. "When districts don’t have the funding to hire enough teachers, class sizes balloon. Districts are constantly playing a game of chess – trying to keep class sizes as low as possible while meeting their obligations to educate every child. When funding gets cut, they’re forced to set class sizes based on the number of children that the fire marshal will allow in the classroom instead of what we know is best for our students."
Efforts to address the issue remain limited but are growing in urgency:
- Gov. Katie Hobbs’ 2024 education budget included a proposed $332 million to address teacher recruitment and retention. However, only a portion of that has been appropriated due to political gridlock.
- The Arizona Teachers Academy offers free tuition to aspiring educators in exchange for teaching in Arizona public schools for an equal number of years after graduation.
- School districts like Tempe Union and Mesa Unified are experimenting with hybrid roles and mentorship programs to retain mid-career teachers.
Still, most experts say it’s not enough.
The bottom line
Arizona’s student-teacher ratio is more than a statistic — it’s a symptom of a deeper divide. Without structural funding reform and long-term investments in the teacher pipeline, the gap between public and private education will continue to grow, along with the consequences.
For most Arizona students that means larger class sizes, fewer individualized supports and even more barriers to success.
Editor’s note: A grant from the Arizona Local News Foundation made this story possible. The foundation awarded 15 newsrooms to pay for solutions-focused education reporters for two years. Please send your comments to AzOpinions@iniusa.org. We are committed to publishing a wide variety of reader opinions, as long as they meet our Civility Guidelines.
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