For English or Social Studies teachers (especially those frothy AP types), the Holy Hand Grenade of rapport-killers is the Five Paragraph Essay. Come out in favor, come out opposed, or simply mention it in passing, and off the rest of us will go. Only Wikipedia and Teach For America have achieved similar infamy for their ability to produce pseudo-intellectual chaos and mutual hostility, online or in the teachers’ lounge.
Honestly, you’d be better off bringing up religion, immigration, or abortion. Fewer emotions or deeply entrenched convictions in play that way.