No, this is unconstitutional. However in the past week, kids in Liberty High at Bethlehem, PA are being threatened with write ups and detentions for this. It seems they've never heard of the amendments. Freedom of speech can be interpreted as much more than speech. Perhaps it is this students speech. Perhaps this student has religious problems with the pledge of allegiance pushing the words 'under god' into the mouths of kids all over America every weekday morning.
The student involved is backed by his good friends who are a part of the 229 Brigade. They are surely sticking together. They've been harassed before on the same sort of ridiculous terms. Both times they've handled it very well. This time might get some coverage if the school board doesn't see whats going on. They'll be taking this to ALCU if they keep getting hassled about this unconstitutional matter of trying to keep church and state together.
Possibly if there is a case in Pennsylvania it will clear things up for them in their area. Even still many people remain ignorant to their rights. Some believe that it is 'the law'. While talking to administrators about this about a year ago, they'd swore on everything that it is 'the law' to stand for the pledge of allegiance. It in fact is not. In my state of Virginia there had been a case in 2005 in the capital Richmond. The question was 'is it a requirement to stand for the pledge of alligence'? The answer -no. They found it unconstitutional and said that it went against the first amendment.
You can see some of what is at face here: http://www.aclu.org/religion/schools/163