BARTOW, Fla. — Police say a Bartow High School student hoping to improve her math grades through extra credit instead got a lewd request from her teacher.

Isaac Nathan Tillis was arrested after repeatedly telling student she could earn an “A” if she gave him oral sex. He lured the girl into a teacher’s lounge bathroom on Wednesday, but once inside police and the girl sprung a trap.

The 16-year-old was wearing a hidden listening device, which recorded Tillis’ proposition after he dropped his pants, police say. The 29-year-old teacher had also scribbled his request on a hall pass, an arrest report states.

Officers arrested Tillis and charged him with soliciting a lewd sex act from a minor.