Minority cultures and relations, sociology homework help

What does it mean to say that race is an idea, not a fact?  What does it mean to say that race has been socially and politically constructed?  Provide an example of the social construction of race.  Do some social and natural scientists question whether the term race is a meaningful concept? 

References:

Farley, J. (2012). Majority-Minority Relations (6^th ed., p. 7). Upper Saddle River, NJ: Prentice Hall.

Fox, H. (2014). When Race Breaks Out (2^nd ed.) New York, NY: Peter Lang Publishing