Students, tests and cash were the perfect variables to fatten high school math teacher Jeff Spires’ wallet, officials said, but administrators pulled the plug on him after several students brought his alleged pay-for-grades scheme to their attention.

Spires, who taught at Charlotte County High School in Charlotte County, Fla.,  was suspended without pay on Oct. 14 and resigned two weeks later.

He had been a teacher in the district since 2002 and told school officials he changed grades for money because he was having financial trouble amid a bankruptcy, arrests and jail time.

“Maybe I see the kids are as desperate as I am,” he told the school’s investigators.

According to a report issued by the school and shared by ABC affiliate WZVN in Fort Myers, Fla., Spires admitted that “he had taken money from two different math students in exchange for improving their grades in math class.”

All students had to do was staple the cash to the test or quiz they wanted Spires to amend, according to the report.

One unidentified junior reported paying the teacher as much as $40 at a time on two separate occasions in exchange for improving a couple of grades on his quizzes and tests. The student ended the quarter with a B, when he actually deserved a C for his work, the school found.

A senior also paid $15 and $30 for his grade to be improved on a quiz, officials found. However, the money did not impact his quarter grade.

“This is one of the most disturbing events I’ve seen in my 40 years,” Douglas Whittaker, Charlotte County Public Schools superintendent, told WZVN.

School officials reported that Spires did, however, turn down an offer of $200 from a senior to change her quarter grade from a B to an A, because the grades had already been recorded.