Earlier quoted context omitted.
Unfortunately, not all U.S. states give students this right. When I was co-editor of my high school's student newspaper, every issue was subject to administrative review. Our principal literally read every issue prior to publication and told us what could and couldn't be run.
Actually we learned in our high school journalism classes that these protections are federal and based off of court cases. Part of our high-school journalism curriculum was learning the court cases that protected our rights as high-school journalists from school administration interference. Of course, a school intent on interfering with a newspaper is probably not going to make that part of the curriculum.
There is a New Voices movement in multiple states to strengthen students' rights regarding school newspapers: http://www.cjr.org/united_states_project/new_voices_campaign...