It is a good idea to write a term paper using a historical perspective. I would start with choosing the exact type of media. It can be something like Hollywood films, sitcoms, chat shows or even advertisements.

You should think of something you like or know pretty well. Then, you will simply look into the way the image of a person of color has changed within some period. Of course, do not forget about reasons for the change.

Or you can choose one period and analyze it.

You can think of such things as stereotypes, misrepresentation, bias. You can also write about the difference between the representation of females vs males pertaining to some minority groups.

As for the specific group, you can choose from African Americans or Native Americans, Hispanic or Asian people. You can also compare some of these groups.

Do you need to stick to the US? You could choose another country or even two countries. I think comparing the way minorities are represented in different countries can be a treat for you and your professor.

Of course, you should address your professor and make sure the topic is appropriate. Though, it can be interesting to choose an ethnic group and analyze the way it is represented in different countries (where they are minorities, of course).

In fact, this is a stunning topic, and you can focus on many things. You can narrow it down to the analysis of a particular type of media. For example, it can be sitcoms or video games, news or films.