A landmark case challenging how Pennsylvania pays for public education and highlighting deep disparities between wealthy and poor districts goes to trial Friday, with the potential to affect every student, school, and taxpayer throughout the state.

The lawsuit — brought seven years ago by six school districts, including Delaware County’s William Penn; parents, including one from Philadelphia; and the Pennsylvania Association of Rural and Small Schools and the NAACP-Pennsylvania State Conference — alleges Pennsylvania’s school funding is both inadequate and inequitable, violating the state constitution.

At the heart of the case are wide gaps in resources between school districts — the product of a long-ingrained funding system that relies more heavily on local taxes than all but six other states and that plaintiffs say discriminates against children and burdens taxpayers in lower-wealth communities. Lower Merion, for instance, has more than $31,000 to spend per student because it can reap more in property taxes — even at lower rates — compared with poorer districts like William Penn, which has $18,000 per student.

Plaintiffs contend the funding system disproportionately harms children of color: Half of Pennsylvania’s Black children and 40% of Hispanic children live in the poorest 20% of districts.

“It’s a story where children who need the most often get the least,” said Mimi McKenzie, legal director of the Public Interest Law Center, which filed the lawsuit in 2014 along with the Education Law Center. Besides William Penn, the five other districts suing are the School District of Lancaster, the Greater Johnstown School District, the Wilkes-Barre Area School District, the Shenandoah Valley School District, and the Panther Valley School District north of Allentown.

The trial, which is being heard by a Commonwealth Court judge in Harrisburg, is being closely watched by schools statewide. “It would be a game-changer to this community,” said Upper Darby Superintendent Dan McGarry, whose district has $16,000 to spend per student — in the bottom 10% statewide — despite taxing residents at one of the highest rates in the state.

Over the next eight to 10 weeks, lawyers are expected to call dozens of witnesses, from local school administrators and state education officials to experts in funding, poverty and learning, testifying to mountains of reports and statistics on Pennsylvania’s public education system.

Nationally, court mandates have significantly shaped school funding. In 28 states where Supreme Courts’ decisions overhauled funding systems between 1971 and 2010, researchers found gaps between low- and high-income districts decreased, and linked spending increases to improved school quality and better student outcomes.

But any changes in Pennsylvania wouldn’t be immediate, given likely appeals. And if the court rules in favor of plaintiffs, it would likely fall to the legislature, which controls the state budget, to come up with a solution. That could result in an increase in or a reallocation of what the state spends on public schools, making property taxes a lesser piece of the funding pie — although it’s too early to know how that would pan out.

While plaintiffs say inadequate funding has led to poor academic results in lower-wealth districts, Republican legislative leaders who are defendants in the case argue more money wouldn’t necessarily lead to better outcomes.

They also point to Pennsylvania’s overall school-funding levels: The state ranks in the top 10 nationally in average spending per pupil, though it trails other Northeastern states including New York, Connecticut, New Jersey, and Massachusetts.

That figure includes local spending, which varies widely. In terms of state spending alone, Pennsylvania ranks 19th in state revenue given out per student, according to a legal filing by House Speaker Bryan Cutler.

“The Pennsylvania Constitution does not require a public school system that is beyond criticism,” Cutler, a Lancaster County Republican, said. “Nor does it require the General Assembly to cure all of the economic, social, community, family, and personal factors that cause students … to succeed at different rates.”

Democratic Gov. Tom Wolf and the Pennsylvania Department of Education are also defendants in the case. But Wolf has agreed with plaintiffs that funding affects achievement and that more needs to be done to address resource gaps between schools.

“While Gov. Wolf’s budget has restored funding that was reduced by the previous administration, this increase in funding has not solved the various difficulties schools face,” said spokesperson Beth Rementer, adding that Wolf acknowledges “inequities in the current system of school funding.”

Pennsylvania’s school funding has long been contentious — and has previously faced legal challenges. Unlike in other states, Pennsylvania courts rejected past cases as outside their purview.

But that changed in 2017, when Pennsylvania’s Supreme Court overturned an earlier Commonwealth Court ruling and said it was the court’s role to assess whether the state was providing the “thorough and efficient” education guaranteed in its constitution. The decision revived the current lawsuit, sending a strong signal the court was open to plaintiffs’ argument.

Republican lawmakers argued unsuccessfully to toss the case in light of a 2016 school funding formula that takes into account issues such as a community’s poverty level, its number of English-language learners, or even the expenses of running school buses long distances in rural areas.

That formula, however, applies to only a fraction of state education funding. Because Pennsylvania for years had been funding districts based on what they got from the state the year before — regardless of whether they had been growing or shrinking, or whether poverty levels had changed — applying the formula to the state’s entire $7 billion contribution would have meant some districts lost money, a political hot potato that has plagued efforts to change the system.

As a result, plaintiffs say the current system is still shortchanging districts with the greatest needs.

For a case all about money, the suing schools and the GOP opponents don’t seem to disagree all that much about funding figures.

Plaintiffs are citing a 110-page report by Matthew G. Kelly, an education professor at Pennsylvania State University, who found the state’s richest schools as a group spent nearly $5,000 more per year per student than the poorest. For his analysis, Kelly divided the state’s 500 public school districts into five groups with roughly the same number of students in each.

Kelly found that the wealthiest schools spent almost $22,000 per student annually vs. just under $17,000 for the least affluent. Lawyers for the GOP did not respond when asked whether they had a rival analysis to share.

A conservative think tank in Harrisburg, the Commonwealth Foundation, has contended the spending gap between rich and poor is much smaller — $1,500. Its analysis, however, groups school systems together without taking into account their relative student populations.

Kelly’s analysis argues the difference between what schools have and need is $4.6 billion — using a study commissioned by the legislature more than a decade ago to calculate the cost of adequately educating students. Based on that measure, which accounts for greater needs of students in poverty, the funding gap between the richest and poorest districts is wider — growing to $7,800 per student.

Republicans indicate they will challenge that analysis as “deeply flawed” and unrealistic.

But districts like Upper Darby, where 68% of students come from low-income families, say something dramatic is needed. Though the district falls near the bottom 15% of the state’s poorest, it gets less state aid per student than more than 60% of districts.

Of Upper Darby’s 13,000 students, 10% are English-language learners, who speak more than 90 languages. The district is required to administer a host of tests to assess their proficiency. In the classroom, teachers like Jen Rodgers are navigating how to reach all of them.

Rodgers, who teaches social studies at Upper Darby High School, had 30 students in one of her classes for most of the fall. Rosters constantly shift — 13 students, all with differing language needs, have joined her classes in the last 11 weeks.

“Google Translate has been a blessing, for sure,” said Rodgers, who speaks Spanish but not Bengali or French, the other most common languages among her students. She tries to help them individually but can’t get to everyone: “You get one to two students to understand — right behind your back are 28 students who also need attention.”

McGarry, the superintendent, says he can’t justify class sizes smaller than 25 at the high school because he needs to prioritize staffing at the youngest grade levels to ensure those students learn to read.

“We’re understaffed in every way, shape, and form in our school district,” McGarry said.

Inadequate funding has “forced the district to make bad choices no one should have to make, to make choices that other places don’t have to make,” said Uri Monson, the Philadelphia School District’s chief financial officer.

Philadelphians have long railed against the district’s process of “leveling” — shifting teachers more than a month into the school year, based on enrollment fluctuations. The disruptive process means that some children lose their teachers, typically in October. It’s a process many suburban districts don’t need to employ: If fewer children than anticipated show up, they just have smaller class sizes.

The school system was able to halt leveling this year because of federal relief money. But while school districts are getting a windfall in pandemic aid — $1.2 billion in Philadelphia alone over several years — many are reluctant to use it to boost staffing, given its one-time nature. The Philadelphia school system’s annual budget is $3.4 billion.

Students who have witnessed years of shortages recognize the dilemma, Monson said. When he and Superintendent William R. Hite Jr. were talking to high school students about how they’d like to see the district spend the federal money, several told the officials not to use it on things they’d have to take away from kids once the money ran out.

”They said, ‘We’ve lived through that,’” Monson said.

Karlo Case, a sophomore at Sayre High in West Philadelphia, says what currently exists is unacceptable. There aren’t many advanced classes or extracurricular activities available to Case, a strong student. There’s no functioning library or librarian. And the building is in rough shape.

In court filings, Republican legislative leaders indicate plans to call expert witnesses who will say there is “no meaningful relationship” between what Pennsylvania districts currently spend and student test scores, and “no empirical consensus” that smaller class sizes boost student learning.

They argue that funding disparities are a matter of local control — with Cutler contrasting wealthy Lower Merion with the Panther Valley district, one of the plaintiffs.

While Lower Merion’s $31,000-per-pupil revenues dwarf Panther Valley’s $18,500, Cutler said this reflected the choice of Lower Merion to spend money on “educational luxuries.” (Panther Valley’s tax rate is in the top 10 statewide and nearly doubles Lower Merion’s, which ranks in the bottom 40%.)

Districts like Upper Darby see a deep unfairness in how challenged they are to offer programs that better-funded districts can more easily provide — and how they’re then judged as inferior. “I can’t run AP Bio when I have 35 students in algebra readiness,” said Upper Darby High School principal Kelley Simone, describing a constant juggling of class sizes.

That affects the district’s ratings, and in turn its real estate prices and tax base, she said — only making it harder to raise what it needs.

“It’s just this vicious cycle,” she said.