PORT ST. LUCIE, Fla. (CBS Local) — A teacher in Florida says she was fired for refusing to give students grades on homework that wasn’t turned in.

Diana Tirado got a job at West Gate K-8 School in Port St. Lucie in August teaching history to eighth grade students. She says she assigned an “explorer notebook project” to her students and gave them two weeks to complete it. However, several of her students didn’t turn in the assignment.

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When she asked administrators what to do, she says she learned of the school’s “no zeros” policy, as reflected in the school’s student and parent handbook, in which the lowest grade allowed to be given to students is a 50 percent.

But Tirado said she refused to give students half-credit for doing nothing.

Tirado was terminated on Sept. 14. No cause was mentioned in a letter from the principal because she was still in her probationary period.

“There is no District or individual school policy prohibiting teachers from recording a grade of zero for work not turned in,” said Kerry Padrick, chief information officer for St. Lucie Public Schools.

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Despite the statement, the Florida teacher claims she was advised to never give out a zero. On her last day, Tirado wrote a message to her students on her white board before she left.

She wrote: “Bye, kids. Mrs. Tirado loves you and wishes you the best in life! I have been fired for refusing to give you a 50 percent for not handing anything in.”

Tirado sent out a picture of it through a class app and several students responded in support.

“You were right about not giving people 50s because why would you give them half credit for doing nothing?” wrote one student.

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Tirado also shared it on Facebook. It’s now been shared more than 500 times.