A preliminary study released this week concluded that students who switched to private schools using the state's voucher system were likely to experience an initial drop in math scores before rebounding academically over time.
Researchers from Notre Dame and the University of Kentucky analyzed ISTEP state assessment scores from around 3,300 students between third and eighth grade qualifying for free or reduced lunch in Indianapolis between 2011-12 and 2014-15.
The authors also conducted more than 100 interviews in 13 private schools, where students often found it a challenge to adjust to homework at the schools.
"It's not just the students that have to adjust over time," said University of Kentucky professor Joe Waddington, one of the study's authors. "Schools as a whole (need) to make a huge adjustment to better serve students. Some private schools adapted faster than others."
The most significant drop in math scores happened in the initial one to two years when a child first attended a private school. English Language Arts test scores were largely unaffected, the study showed. For students that remained in private schools over the three- to four-year course of the study, test scores rebounded on level with public school peers, the study showed.
Special education students showed a slight drop in English Language Arts. Students attending Catholic schools generally showed small gains in English, according to the study.
However, many low-achieving students returned to public schools where they lost moderate to substantial academic ground, according to the study.
More than 34,000 students have used Indiana's voucher system in more than 300 schools – the nation's largest program. Since the law was broadened in 2013-14 to drop the requirement for students to first attend public schools, more than half of students using a voucher in 2014-15 have not attended public school, according to the study.
The study also found that trends were consistent for students regardless of racial, ethnic or socio-economic backgrounds, which likely could point to factors within the school itself, such as comparable curriculum, instruction, teacher quality, or other issues related to switching schools, according to the study.
"I do think that is a surprising finding," he said. "I think it says something more about how private schools funding (and have) adapted" to students with vouchers.
The study has not yet been published in an academic journal and is now being peer-reviewed.
Molly Deuberry, a spokeswoman for the Indiana Department of Education said via email that Superintendent of Public Instruction Jennifer McCormick's office would not comment on the study before it was peer-reviewed and published.
In April, McCormick told the Post-Tribune that she supported the principle of school choice and the voucher system, but also wanted to ensure accountability for those schools.