Students right to moment of silence?

Our community lost a father, two sons, the mother is in critical care and a teenager daughter being the only survivor beside her mother in critcal care due to a fire that authorities have said is the worst they have seen. The school that the girl goes to and the brother went to has denied the students request for a moment of silence for the loss of their peer. We are in Pennsylvania and I am wondering what rights the students have to demand this moment of silence for this tragic loss. I have searched and searched with no luck. Any help would be greatly appreciated.|||Every school should have the right to a Moment of silence where I go to school it is required I live in Oklahoma and everyday we have two minutes of silence!