Breaking The Curve Why A Straight Scale Is Appropriate In Engineering Courses

Many instructors have a tendency to place students on a curved grading scale based upon statistics and the average student's performance during the semester. This is often done because it makes it easy for professors to assign final grades. Professors can also feel more comfortable about their exams because any unfair questions will be normalized out through the curve. It is comfortable to use a curved scale, too, because many of the courses the instructors had were taught on curved grading scales. There are several problems with adopting a traditional curved grading scale within engineering courses. We will highlight several points that should demonstrate why a straight scale is more appropriate. Curved grading scales are based upon statistical assumptions that the class is large and that the student body is randomly dispersed over a wide range of performance. However, most engineering courses do not have hundreds of students in them so the size of the class could skew the results. Another problem is that engineering does not attract a random sample of student abilities. Within the three universities that I have been affiliated with, each school had a predominantly higher percentage of honors students enter the engineering program than the general student population. In the case of the University of Arizona, 18% of students are in the honors program, but 48% of chemical engineers are. One should ask whether it is appropriate to curve the scale when most of the students are of very high ability. This would punish students for being bright enough to choose an engineering career. So, one should question how large the class is and the raw student caliber entering into the class before using a curved scale.