Possible Reasons for a Negative Skewed Bell Curve from an Assessment

When a bell curve is skewed negatively on any assessment, I as the teacher have to be worried. The distribution will show a long tail in the negative direction and the data will point out that most of the students did well on the formative assessment and only a few did poorly (Donnelly, 2004). This would make me question either my curriculum or my assessment. In questioning my curriculum, I would have to figure out if cheating was involved or if the there was a particular motivation for the students to do well on the test. In my experience, during football season, boys will try to achieve better scores because of the threat of being thrown off the team, but to be valid in this scenario, they would have to be a large population of boys in the class that had a sports interest. Another life experience idea comes to mind. I would have to look at the population of special needs in my class and find out if whether I had a low population of special needs students in that class, and if so, compare it the populations of classes before who took the same assessment.

The curriculum would have to be reexamined and realigned with the learning abilities and the motivation of the students. The score might have failed to meet the mean because the curriculum was set for lower ability students that were less motivated. One method that I have seen other teachers use to correct this problem in higher educations is to adjust the assessment instead of the curriculum. If there were a high number of students that missed a certain question, then that question was either taken from the exam or reworded to receive more positive answers. By reworking the exam and viewing the statistics each time it was taken, the teacher would be able to have the types of questions that would show a mean but still include a variety of question types that aligned with Bloom taxonomy of learning (Seddon, 1978).



Donnelly, R. (2004) The Complete Idiot’s Guide to Statistics. Alpha Publications. Retrieved on September 12, 2009 from googlebooks.com


Seddon, G. (1978). The properties of Bloom’s taxonomy of educational objectives of the cognitive domain. Review of Educational Research 48(2). Retrieved on September 12, 2009 from Sage Journals Online.


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