Correction: Assigned video on Tinker v. Des Moines contained an error. The ruling did NOT indicate the wearing of armbands WAS pure speech, but rather is was closely akin to pure speech.
The ruling did indicate the following:
"As we shall discuss, the wearing of armbands in the circumstances of this case was entirely divorced from actually or potentially disruptive conduct by those participating in it. It was closely akin to "pure speech" which, we have repeatedly held, is entitled to comprehensive protection under the First Amendment.