Betsy DeVos got off to a rocky start with families of disabled children when she acknowledged being confused by a question at her confirmation hearing about a federal law that has governed special education since 1975.

Now that DeVos is on the job at the U.S. Education Department, advocacy groups say they will be watching closely to see how much the billionaire school choice champion has learned and how her philosophy will affect the more than 6.5 million public school students who need special support in class.

“It’s fair to say that there’s a high level of anxiety from our members,” said Denise Stile Marshall, executive director of the Council of Parent Attorneys and Advocates, which opposed DeVos’ nomination.

As education secretary, DeVos leads the department charged with enforcing the federal Individuals with Disabilities Education Act, or IDEA. The 42-year-old law entitles children who struggle to learn or have medical or developmental challenges to a “free appropriate public education” aligned with their state’s academic standards. It includes services tailored to each child’s needs and in the “least restrictive environment” where those needs can be met. To help states meet the excess costs, the federal government supplied $11.9 billion in funding in 2016.

During her January hearing DeVos exasperated lawmakers and parents when, asked whether schools receiving taxpayer funding should be required to comply with IDEA, she replied it was “best left to the states.” When asked whether she was aware IDEA is a federal law, she answered, “I may have confused it.”

Amid the backlash, DeVos wrote in a letter to Sen. Johnny Isakson of the Senate education committee that she is “committed to enforcing all federal laws and protecting the hard won rights of students with disabilities.” Half of the Senate voted against her confirmation, leaving Vice President Mike Pence to cast a tie-breaking vote to give her the job.

Apparent technical issues that blocked public access to an IDEA-related website did nothing to instill confidence. “It was not taken down and we are working to resolve ASAP,” the department tweeted Feb. 8, the day after DeVos was sworn in. As of Monday, traffic was being redirected to a different department site, which included a note saying the department was working to resolve the technical issues.

Sens. Patty Murray and Maria Cantwell, both Democrats from Washington state who voted against DeVos, wrote to the secretary Friday requesting an explanation and assurances that missing information would be restored.

The department did not immediately respond to a request for comment Monday.

About 13 percent of the nation’s public schoolchildren receive special education services. The largest segment, 35 percent, have a specific learning disability that may disrupt their ability to write, spell or do mathematical calculations. About 21 percent have speech or language impairments and the balance have other health impairments, autism, emotional disturbances, developmental delays or intellectual disabilities, according to federal statistics.

The graduation rate among students with disabilities was 63.1 percent in 2013-14, compared with the national average of 82 percent.

DeVos’ letter to Isakson was not enough for some advocacy groups, who also worry about DeVos’ support for using public funding for vouchers to cover education at private schools that may not be subject to the rules of the IDEA civil rights law.

“Secretary DeVos has not expressed a strong commitment to public schools or to ensuring that all students, including students with disabilities, receive equal educational opportunities,” the American Association of People with Disabilities said in a statement to The Associated Press this week. “To date, she has not said or done anything to alleviate these concerns.”

But Ohio parent activist Tera Myers, who attended DeVos’ hearing in Washington, D.C., said she is excited about DeVos and that school choice programs like those DeVos supports helped her son with Down syndrome when she became disillusioned with the education he was getting in the public system. Myers’ son attended a private school under Ohio’s state-funded Jon Peterson Special Needs Scholarship program, which pays for tuition and services at non-public schools. Accepting the scholarship meant the public district was no longer responsible for providing the free appropriate public education outlined by IDEA, something Myers said she freely accepted.

“For students with disabilities, I really believe even more so, that parents should have the option to choose. I understand that not every parent wants that choice and that’s OK, and that’s why it’s important for there to be a myriad of choices for us.”