The teacher says, “Good morning, boys and girls.”
The teacher says, “Good morning, white children and black children.”
One of these is perfectly acceptable; the other is startling and not acceptable. Yet each implies that there are important differences, and since it is coming from a teacher, that these differences affect learning ability.
This provocative point came out in this afternoon's NPR program Talk of the Nation: Science Friday. The topic was Gender Differences and Cognitive Abilities. Online audio of the program will be available after about 6pm today.