The tuition's and fees for any given institution of higher education are theoretically the same for all attending students. Colleges and universities, however, routinely charge different tuitions and fees to different students. These differences show themselves in various ways. In-state, and out of state status, differences in financial position of students’ families, merit based awards, sports’ scholarships and similar devices are among the methods that effectively change the price of same education to be different for different students. Explain what is this practice called and what are some of the motifs behind this behavior by colleges and universities.