Instead, the purpose of curving grades is to define relative achievement within the class. Whether or not this is best represented by a single test is another question, but it seems to me that grades are not merely a tool to pat people on the back for a job well done. I remember in college that the most popular classes were those taught by professors who were notorious for easy grading. If everyone gets a good grade though, what does that actually say? A B+ in a class where the average grade is an A should be a lot less meaningful than a B in a class where the average is a C+. The curve eliminates this problem.