Answer:
The above quote is from the Supreme Court case Tinker v. Des Moines Independent Community School District, in which the Court ruled that students do not shed their First Amendment rights to freedom of expression at the schoolhouse gate. However, the Court also recognized that the rights of students in the public school setting are not necessarily the same as the rights of adults in other settings, and must be balanced against the special characteristics of the school environment.
Based on this quote, it is likely that a school action that censors student speech that is inconsistent with its basic educational mission would be upheld by this decision. For example, if a school were to censor student speech that was disruptive, violent, or sexually explicit, or that promoted illegal activity, such censorship would likely be upheld as being consistent with the special characteristics of the school environment and the school's educational mission. On the other hand, if a school were to censor student speech that was peaceful, non-disruptive, and related to a matter of public concern, such censorship would likely be deemed unconstitutional under the Tinker decision.