✔ 最佳答案
As noted in other answers, the primary purpose of school is to teach. How to read, how to write, how to think critically, how to do math, etc.
A school is not a public forum as such limitations on speech do not invade the Freedom of Speech. I think within certain confines students should be allowed to speak freely. Within the classroom, the speech should be confined to the subject being taught and should conform to the rules of polite conversation.
Outside the classroom, and in extracurriculars, the rules should be less strict. However, rules of basic politeness and proper language (e.g. no profanity, no attempts to start a fight, etc.) should still apply.