The first amendment protects several basic liberties that include freedom of religion, speech, press, petition, and assembly. Interpretation of the amendment is far from easy as court case after court case has tried to define the limits of these freedoms.
In this court case a student is punished for posting a blog that used explicit language towards a teacher at the school. This isn't really even the reason the case got attention. The reason for the attention was the banning of shirts that said "Team Avery". The teen sued because she was unable to run for class security. The court ruled that not being able to run for school officers doesn't deal with freedom of speech. The court ruled in the favor of the school every time because they decided the blog could involve or interfere with school work.
I believe the ruling was right because there just isn't a need to talk like that referring anything especially involving a school. I believe student have freedom of speech but not freedom to discriminate on someone because they were doing there job.