Freedom of Speech is relative. Dont believe me review court cases involving yelling fire in a movie theater or even any spoken words that could be considered harmful to a politician or the president. See how well freedom of speech works.
This “lesson” was not properly thought out, and almost appears to have been done to cover up some other possible situation? Those teachers RECORDS are now sealed! Was the teacher involved in something else, were they under review for something, this is an obvisious way to incite a school board to try to take actions under which they would never win.