To encourage critical thinking and competitiveness, I hold up a prize (usually candy or gift cards) that they will receive if they can tell me ONE such "preference." I've never had to give away anything since I started teaching my Race Relations class close to 8 years ago, and I let my students know that fact. We then discuss "preferences" as a class. I provide examples of true dating preferences as characteristics that cannot be solely attributed to a particular race. Examples I give are skin color (dark skin can be found among Black Americans, Aboriginal Australians, Cambodians, etc.), height, eye color, hair color, and body shape, all of which vary more greatly within ethnic/racial groups than in comparison with other groups.
I then bring up a slide that highlights the Zealot/Defensive Stage of the Majority Identity Development Model. It describes this stage in detail by explaining that the Zealot/Defensive Stage ranges between two extreme reactions: Become a zealot for "minority" causes or become defensive about "majority" views, and perhaps, even withdraw from finding out about multicultural views altogether. In becoming a zealot, the person is often reacting to their own, or to the majority culture's collective guilt. Cultural appropriations and/or over-identification of the identified "other" are common manifestations of this reaction. In becoming defensive, the person either attempts to maintain exclusive contact with majority culture individuals, or they try to defend majority values by pointing out all of the "concessions" made by the majority culture for minority cultures (e.g., Affirmative Action, Marriage Equality, etc.).
The final slide asks only one important question: "What do you think such 'racial preferences' in dating is all about?" Students begin to draw connections, including how it can be a manifestation of the zealot end of the Zealot/Defensive stage of the Majority Identity Development Model. When providing other possible motivations for such behavior, students have given potential motivations such as feeling guilty about their own privileged "majority" status; as an act of defiance against a racist and/or bigoted family system; the possibility that it's an act of revenge against an ex who was overtly racist against a specific group; or in cases where people won't date members of their own race - that it's a symptom of internalized racism, prejudice, and/or hatred.
To conclude this often challenging introspective and thought-provoking exercise, I make sure to emphasize an important personal viewpoint with my students. I let them know that the activity they just participated in is not, in any way, designed to deter mixed "race" dating, and that in fat, I endorse and am fully supportive of everyone forming intimate relationships (or not) with whomever they have a connection to. However, I feel that we should all do so for the right reasons (e.g., connection, attraction, etc.), and not because we are dealing with our own reactions to the uncomfortable realization that we have been (as Caucasian, heterosexual, cisgender, and other identified "majority" group members) benefiting from a racist and heterosexist system of oppression, or that (as member of groups other than Caucasian, heterosexual, cisgender, etc.) have internalized the destructive racist, heterosexist, and/or oppressive messages we have been forced to consume throughout our lives that have made us wrongly believe the lie that we are in some way inferior.