In the case of Tinker v. des Moines, how did the Justices defend the armbands students wore in public school?

In the case of Tinker v. Des Moines, the Justices defended the armbands that the students wore in public school as a form of symbolic speech protected by the First Amendment. They argued that students do not "shed their constitutional rights to freedom of speech or expression at the schoolhouse gate" and that the armbands were a form of peaceful, non-disruptive expression of political views. The Justices emphasized the importance of protecting student's rights to express their beliefs, even if those beliefs are controversial or unpopular.