Framed within Schein's culture model, this study re-centres teacher culture as a key variable in pedagogic settings. Teachers' cultures or basic assumptions in a culturally diverse desegregated school are explored as a crucial dictate in the emergence of the context in which teaching and learning materialises. Through engagement in a focused ethnographic exploration, life sciences teachers' basic/fundamental assumptions in desegregated classrooms are identified and interpretively explored to decipher the context they precipitate. Deciphered assumptions included assumptions about social identity, relations, academics, pedagogy, power, and metaphysics.