Answer:
The person above me has a great answer. This is just a copy and paste version of his with a few fixed spelling mistakes and some minor changes to some wording.
The Tinker v. Des Moines case is a landmark decision by the US Supreme Court. This decision defended the constitutional rights of public school students. This case started when Mart Beth Tinker, John F Tinker, Hope Tinker, and Paul Tinker decided to wear a black armband to school to protest against the Vietnam War. The school officers didn’t allow that and asked the students to remove the armbands immediately, they refused and because of that, they were sent home.
The Iowa Civil Liberties Union Filed a suit and then it got to the US Supreme Court it ruled a 7-2 decision.
The majority opinion of the court was based in that the First amendment - that prevents the government from banishing religion, prohibiting the freedom of speech, of the press and other rights - is applied to public schools.
The dissidents' opinion was that disruptive symbolic speech was not protected by the first amendment and that “I have never believed that any person has a right to give speeches or engage in demonstrations where he pleases and when he pleases.” The judge said that this ruling would give an authorization for pupils and students to defy orders of school principals.
The stronger argument is the majority argument. The first amendment is clear that every single American citizen has the right to freedom of speech, also the first amendment doesn't say which place the freedom of speech is not allowed. The students. In this case, did not hurt or say anything to anyone, they simply wanted to wear an armband that symbolized their opinion. It is not correct that school officials that do not agree with that opinion just censor it, creating new rules just because of that. The fact that the students didn’t do anything to harm any other student and didn’t affect the operation of the school was another sign of the illegality of the act of the schools principal, this is also the opinion of the court: materially and substantially interfere with the requirements of appropriate discipline in the operation of the school."