Answer: It established speech rights for students.
Mary Beth Tinker and other students at her junior high school decided to wear black armbands to protest the Vietnam War. The school found out and decided to pass a preemptive ban. The students agreed to take off their armbands, but they wore black clothes for the remainder of the year in protest.
The students then engaged in a four-year legal battle that culminated in the Supreme Court decision Tinker v. Des Moines, which argued that the students were entitled to exercise their freedom of speech and expression in a school setting, as long as it did not disrupt the learning process. The black armbands were not considered to be disruptive, therefore they were protected.