Philanthropist Betsy DeVos, President-elect Donald Trump’s pick for education secretary, did not succeed in getting a school voucher program off the ground in her home state of Michigan.

But her advocacy helped influence the program in neighboring Indiana, which is expansive, entrenched — and could be a model if Trump and DeVos move forward with trying to push a national voucher program.

Here are six important things to know about vouchers in Indiana:

1. Indiana’s program is the biggest in the country — costing local districts students and funding.

It allows thousands of families to have thousands of dollars to send their kids to private schools that they would otherwise have to pay for, or win scholarships to attend. The number of students using vouchers rose from 3,911 in 2011, when the program launched, to 32,686 in 2016.

That total makes Indiana’s voucher program the largest of any state, with nearly 3 percent of kids using public funds to pay private school tuition.

If a public school student applies for and receives a voucher to attend a private school, they take their state funding with them, so districts and schools where those students might otherwise have enrolled shoulder the cost. Voucher advocates argue that schools can handle the loss because they have fewer students to educate. But critics say that isn’t the reality of how school budgets work: If a class loses two of 20 students, its teacher doesn’t see her salary reduced by 10 percent.

Funding issues have fueled criticism of the program. In 2013, the Indiana State Teachers Association filed a lawsuit to stop it, arguing in part that the program caused public dollars to be spent improperly on religious institutions. The Indiana Supreme Court dismissed the suit, but the union has continued to make the argument. And even Jennifer McCormick, the small-district superintendent who, with DeVos support, unseated Democratic State Superintendent Glenda Ritz, has expressed concerns about programs that divert money from public schools.

2. Indiana’s program looks a lot like what DeVos says she wants.

Trump’s proposal is for low-income families to be eligible for vouchers, but his vice president, former Indiana Gov. Mike Pence, has supported vouchers for middle-income families, too. DeVos is more in Pence’s camp, and her political action committee, the American Federation for Children, has poured $1.3 million into local voucher advocacy efforts.

Indiana’s eligibility is unusually wide open. Students who get vouchers don’t only come from families near the poverty line (as in North Carolina), have special needs (as is a requirement in several states, including Florida), or be zoned for low-performing schools or districts (as in Cleveland).

The only restriction is family income, but even there Indiana’s rules are generous. A family of four making less than $44,863 per year can receive a voucher of up to 90 percent of the funding that their local public district would receive from the state. Since 2013, families earning up to $89,725 per year have also been eligible — but they get only half the state aid their district would receive.

3. It is increasingly serving students from middle-class families.

A growing portion of Indiana voucher users are from middle-class families, and growth has been greatest among suburban families.

In 2016, 22 percent of voucher students were from the suburbs, compared to 16 percent in 2011. The portion of voucher users living in rural areas also rose slightly during that time — even though vouchers are often impractical in areas where there are not enough students to sustain multiple schools.

As the proportion of urban families using vouchers fell, so did the proportion of students of color. During the first year, black students — who are 12 percent of the state’s students — made up about a quarter of voucher students in the state. That number is down to 13 percent now. Hispanic student enrollment is down as well, to 18 percent, even as Hispanic student enrollment has shot up across the state in the last five years.

In total, 60 percent of Indiana voucher users are white, and about 31 percent are from middle-income families — not exactly the student population that struggles most in the state’s schools.

4. It has steered students away from public schools — but also probably helped families make the choices they were going to make anyway.

A rationale for vouchers — and one DeVos has offered — is that they let families escape low-performing public schools that aren’t helping their kids. But over time, the proportion of Indiana voucher users moving from public schools has fallen sharply. In 2011, just 9 percent of voucher users had never before gone to public school. That was true for more than half of students using vouchers in 2016.

Another question is whether vouchers allow families to choose private schools they wouldn’t otherwise be able to afford. The evidence in Indiana is mixed: Since the program launched, private school enrollment has grown — but less rapidly than voucher use, suggesting that some new students attend private school because of vouchers, but other voucher recipients would attend private school regardless.

And as is often the case when vouchers are introduced, religious schools have benefitted heavily. Vouchers have allowed some Catholic schools to stave off closure, and parents who use vouchers say the opportunity for their children to get religious instruction at school was the most important reason they chose their schools. Most of the non-religious schools that accept vouchers cost far more than the cost of the voucher, making them unaffordable for low-income families.

Critics of vouchers say the data points add up to a problematic picture. “How many of the kids that are actually receiving vouchers were ever going to go to a public school anyway?” Teresa Meredith, head of the state teachers association, said in June. “I think it shows that it’s really not helping the kids that it was promised to help.”

5. The program has more regulations than DeVos might like.

A hallmark of Devos’s philosophy appears to be opposition to regulation of schools — she recently worked to oppose added oversight for charter schools in Detroit. Ordinarily, private schools in Indiana face very few state restrictions, but schools that accept vouchers must act in some ways like their public school counterparts.

First, they have to get approval from the state to accept vouchers. Once approved, they must be accredited, give the state’s annual test, known as ISTEP; evaluate teachers in part based on student test scores; and receive A-F accountability grades. They’re also vulnerable to consequences if their students consistently post low test scores — including losing their ability to accept vouchers from new students.

The regulations didn’t bother Republican lawmakers because many Indiana private schools already had accreditation and met some of the other requirements to be able to compete in the state’s high school athletics association, according to Republican Rep. Bob Behning.

Voucher schools aren’t allowed to censor materials related to American history and must maintain libraries that include the U.S. Constitution and other documents. (Indiana’s standards do not require teaching contraception, an issue for some private schools in other states with vouchers.)

6. Vouchers haven’t helped students learn more.

One argument that voucher proponents make is that families can choose the schools that are going to serve their children best. But across the country, a growing body of research suggests that vouchers have limited or no effect on student learning. Locally, a new new long-term study out of Indianapolis, done by researchers at Notre Dame University, found that students who switched from traditional public schools to Catholic schools actually did worse in math.

One possible explanation: Vouchers cause students to change schools when they otherwise would not. “All research that we know of is pretty convergent on the conclusion that mobility for students is bad,” said Ashlyn Nelson, an education researcher and professor at Indiana University.