Bennett resigned as Florida's schools chief in August, a few days after The Associated Press published emails uncovering his changes to the formula. Bennett has maintained he did nothing wrong.
Inspector General David Thomas has confirmed that Bennett is the subject of an ongoing investigation but has declined to say specifically what is being reviewed.
Indiana has classified schools based on graduation rates and testing performance since "Public Law 221" was approved in 1999. But Bennett sought more accountability for schools and successfully pushed for a new A-F system.
The grades are used to determine how much money schools get and whether "failing" schools are taken over by private operators. The grades have also become an important tool for realtors and homebuyers.
Indiana's school board had already been tasked by state lawmakers earlier this year with creating a new formula by Nov. 15. That work continues.
The pair of analysts picked by Indiana's Republican legislative leaders to review Bennett's changes took questions from the board earlier Wednesday. John Grew, a former Democratic Statehouse analyst, and Bill Sheldrake, a veteran Republican analyst, walked through their findings in the 58-page report.
The pair found that Bennett and his team rushed to release the school grades last year without properly testing the formula. They also discovered credibility problems with the scoring because Bennett and his team were not telling the public about changes they made.
Sheldrake ended with some final advice for the board as it works on the new grading formula: "Transparency. Transparency. Transparency."