Yes, if you interpret it very, very literally, having a crucifix in a public school classroom goes against the First Amendment. That being said, if the district goes after her, then they must go after
wishing Muslim students an Eid Mubarak, singing Christmas and Hanukkah pieces in school music programs, wishing Hindu or Sikh students a happy Diwali or Vaisakhi...
I don't think she or the Church are being targeted at all, superintendents and school administrations are just trigger-happy. I've met a lot of them.