It is rare that I would quote the ACLU, but I thought that this list of tips from them on the Day of Silence and related matters looked fair.
1. You DO have a right to participate in Day of Silence and other expressions of your opinion at a public school during non-instructional time: the breaks between classes, before and after the school day, lunchtime, and any other free times during your day. If your principal or a teacher tells you otherwise, you should contact the ACLU national office or GLSEN (Benny Vasquez firstname.lastname@example.org, 646-388-8055).
2. You do NOT have a right to remain silent during class time if a teacher asks you to speak. If you want to stay quiet during class on Day of Silence, we recommend that you talk to your teachers ahead of time, tell them what you plan to do, and ask them if it would be okay for you to communicate on that day in writing. Most teachers will probably say yes.
3. Your school is NOT required to “sponsor” Day of Silence. A lot of schools this year are announcing that they aren’t sponsoring Day of Silence due to pressure from national anti-gay groups. But Day of Silence is rarely a school-sponsored activity to begin with — it’s almost always an activity led by students. So don’t be confused — just because your school is saying that the school won’t officially sponsor or participate in Day of Silence doesn’t mean that it’s saying you can’t participate.
4. Students who oppose Day of Silence DO have the right to express their views, too. Like you, they must do so in a civil, peaceful way and they must limit their expression to non-instructional time. They do NOT have a right to skip school on Day of Silence without any consequences, just as you don’t have a right to skip school just because you don’t like what they think or say.
Those who say the DOS is a disruptive activity may not realize that the organizers communicate this to the participants. I was not aware of it either. I do not think this is widely known.