INDIANAPOLIS — Former Indiana schools chief Tony Bennett has asked the state's inspector general to investigate the Department of Education's actions during his tenure after resigning as Florida's education commissioner.Tony Bennett's request Thursday followed an Associated Press story showing that Bennett and his staff scrambled to overhaul Indiana's school accountability formula after learning a charter school founded by a top Republican donor had received a C. Bennett has denied any wrongdoing and says the formula change wasn't directed solely at Christel House Academy. He resigned his Florida post Thursday, saying he didn't want the Indiana emails to distract from Florida's education efforts. Meanwhile, the American Federation of Teachers says Indiana should immediately suspend its A-F school grading system because of the controversy. The union issued its call at a Statehouse news conference Thursday, just hours after Bennett resigned as Florida's education commissioner. Indiana uses A-F grades to determine which schools get taken over by the state and whether students seeking state-funded vouchers to attend private school need to first spend a year in public school. They also help determine how much state funding schools receive. His letter to Indiana Inspector General David Thomas calls emails cited in the story a "small snapshot of a long, arduous and iterative process" of implementing Indiana's A-F grading. Bennett was defeated last year in his bid for re-election as Indiana's top educator. Before taking that office, Bennett was a longtime southern Indiana teacher and administrator. He served a short tenure as superintendent of Greater Clark County Schools.