Livia Gershon writes: “It’s Thanksgiving season, which in many elementary schools means it’s time to celebrate Native Americans. And yet the books teachers and administrators choose for these units sometimes convey unintended messages, stereotyping Native cultures. That’s a situation that anthropologists Valerie Lambert, an enrolled citizen of Choctaw Nation, and Michael Lambert, an enrolled citizen of the Eastern Band of Cherokee Indians, came face to face with in 2011.”