All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
We have previously underlined the prohibition of listening to music in fataawa 81239 and 81545. Hence, it is incumbent on you to avoid listening to music to the best of your ability. What you should do is to contact the school administration, if you can, and try to clarify the prohibition of music to them. If you cannot do that, then you should forbid it in your heart. If you happened to come early, you should try to avoid being in the field until the playing of music is over as much as you can.
You should know, though, that listening to songs or to music with lyrics containing prayers to Allaah is not an act of kufr (disbelief) that takes the listener or the singer out of the fold of Islam as long as it does not involve ridiculing or belittling the remembrance of Allaah and supplication.
Allaah knows best.