National School Boards Association on Teacher Speech Rights:

  1. What are the limitations on the First Amendment rights of employees?

    School district employee speech is protected under the First Amendment if the employee is speaking as a private citizen on a matter of public concern and the employee’s interest in commenting on matters of public concern outweighs the interests of the school district in promoting the efficiency of its operations or services.

  2. Does it matter if the employee is a teacher or other school-related employee, like a bus driver or cafeteria worker?

    No. The Supreme Court’s framework for government employee free speech rights applies to all public employees.

Source

When assessing whether a public school can regulate an individual instance of employee speech, ask:

See the National School Board Association’s 2018 First Amendment Guide for more info.