John O’Connor and Trevor Aaronson: A state inquiry found that online educator K12 Inc. employed three teachers in Florida who lacked proper certification to teach some subjects.

Trevor Aaronson and John O’Connor: Student-teacher ratios at K12, the nation’s largest online educator, are nearly twice as high as Florida’s state-run virtual school, according to internal company documents obtained by FCIR and StateImpact Florida.

John O’Connor: K12 said the company always uses Florida-certified teachers, but the company’s internal review found “minor mistakes” in matching grade and course certifications to students.

Trevor Aaronson: K12 did not believe the Florida Department of Education’s probe was “material” to investors.

Trevor Aaronson and John O’Connor: The Florida Department of Education has launched an investigation of K12, the nation’s largest online educator, over allegations the company uses uncertified teachers and has asked employees to help cover up the practice.

Ralph De La Cruz: The Miami Herald shines light on a $400 million charter school industry that has grown out of control with little or no oversight.

Mc Nelly Torres: The incident illustrates how confused local school districts in Florida have been about federal regulations governing education funds and the reporting requirements that came with the 2009 stimulus bill.

Mc Nelly Torres: After burning through stimulus money, Florida’s public school systems must learn difficult financial lessons.