That's the determination of a New Jersey high school principal and, despite the clarity of the U.S. Constitution on the issue, it has become the determined belief on the part of school officials across the country.
Therefore, when a student wants to speak of Jesus in a report or in a speech, when a student wants to pray or join in a Bible study or, as in this case, when a student desires to participate in a peaceful pro-life action, secularists in the system become tyrannical opponents of religion.
Thankfully, lawyers associated with the Alliance Defense Fund are working to protect this young girl's Constitutional rights (and ours too). Check it out. And, if possible, send them a check to help out with their critically important service.