I agree with Perchik, in a public high school while you legally still have the right to free speech, if your freedom of speech is deemed to be an interference or disruption of learning, then the school system as an entity, has the right to prevent your use of free speech. However if you feel that such power is being improperly administered you can legally appeal the school’s prevention of free speech. In private schools, it is a completely different matter, it is really dependent on each school, so the best thing to do if you are in a private school, is to talk to the head of the school.
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Trust me on the public school thing, I work for the student newspaper and we have had many issues with freedom of speech and the school’s ability to prevent a student’s use as such.(At least in Massachusetts)