TAMPA, Fla. (WFLA) — A Florida school district is being sued after it banned a popular children’s book for certain age groups.

NBC News reported that six Florida students, their parents and two authors sued the Lake County school district Tuesday for banning students in kindergarten through third grade from accessing “And Tango Makes Three.” The book, released in 2005, is based on a true story about two male penguins at New York City’s Central Park Zoo who adopted and raised an orphaned penguin chick named Tango.

When the school district members decided to ban the book, they said their decision was based on Florida’s Parental Rights in Education law. The law prohibits “classroom instruction by school personnel or third parties on sexual orientation or gender identity” in kindergarten through third grade “or in a manner that is not age-appropriate or developmentally appropriate for students in accordance with state standards.”

The news outlet reported that Tuesday’s lawsuit argues that the law is “vague and overbroad” and that the district, by restricting access to “And Tango Makes Three,” violated the First Amendment.

“By discriminating based on content and viewpoint, it infringes the authors’ right to freedom of expression,” the suit says. “By restricting access to a book, which was previously freely available, for narrowly partisan and political reasons, it infringes students’ right to receive information.”

In a joint statement to NBC News, the authors said they sued “to affirm the American principle that no child should be denied access to age-appropriate information in school because of the beliefs and biases of some; to defend students’ right to read a heartwarming story of difference, acceptance, and love; and to protect authors from censorship rooted in intolerance.”

Six students joined through their parents or legal guardians because they’re interested in reading the book for a variety of reasons, NBC News reported.