UPDATE: Obama assassination teacher placed on leave by district

It's certainly one way to get students to pay attention.

Trouble is, it's bound to get the Secret Service's attention too.

An Alabama geometry teacher, in an apparent effort to teach his students about parallel lines and angles, used a theoretical assassination attempt on President Barack Obama to demonstrate the angle at which a gunman would have to shoot the president.

"He was talking about angles and said, 'If you're in this building, you would need to take this angle to shoot the president,' " said Joseph Brown, a high school senior in the geometry class told The Birmingham News.

After the class, word passed up the grapevine to the local branch of the Secret Service, who told the paper they'd questioned the instructor but weren't taking any action.

"We did not find a credible threat," Special agent Roy Sexton, who leads Birmingham's Secret Service office, was quoted as saying. "As far as the Secret Service is concerned, we looked into it, we talked to the gentleman and we have closed our investigation."

The local superintendent said he intended to have a "long conversation" with the teacher.

"We are going to have a long conversation with him about what's appropriate," Superintendent Phil Hammonds told the News. "It was extremely poor judgment on his part, and a poor choice of words."

The teacher's name was not identified by the paper. He remains employed.

This isn't the first time this year the Secret Service has investigated potential threats. In March, the agency probed several Twitter posts suggesting taking the President's life: "We survived the Assassinations and Lincoln & Kennedy. We’ll surely get over a bullet to Barrack Obama’s head� and “You Should be Assassinated!! @Barack Obama.�

Last year, a teenager was also questioned for a Facebook poll, which asked: "Should Obama be killed?"

No charges were filed in the case.