[Jonathan Zimmerman teaches history at New York University and lives in Narberth. He is the author most recently of "Small Wonder: The Little Red Schoolhouse in History and Memory" (Yale University Press). He can be reached at jlzimm@aol.com.]

In 2001, high school English teacher Shirley Evans-Marshall gave her class a copy of the American Library Association's "100 Most Frequently Challenged Books." She asked her students to choose a book on the list and explain why it was controversial.

But the assignment itself was too controversial for Evans-Marshall's Ohio school district, which declined to renew her contract.

Evans-Marshall sued, claiming a violation of her First Amendment rights. And last year, a federal appeals court ruled that she didn't have any - at least not in her own classroom.

"The right to free speech ... does not extend to the in-class curricular speech of teachers in primary and secondary schools," the court declared.

That's why teachers still need collective bargaining, which lies at the heart of this winter's bitter battles over public-employee unions....