The following is the Mount Vernon Board of Education’s “Academic Freedom of Teachers” policy (there is no administrative guideline for policy 3218):
Policy 3218 - Academic Freedom of Teachers
The freedom to speak and share ideas is an inherent precept of a democratic society governed by the will of the majority. Teachers and students need to be free to discuss and debate ideas.
When ideas that may be controversial are introduced, teachers, while having a right to their opinion on the subject, shall state it as such and they should be objective in presenting various sides of issues.
See here for a PDF compilation of the “Bylaws & Policies and Administrative Guidelines” adopted by the school board.