I am teaching a programming course at the university where I am working. I would like to do a statistical test to see if students marks (exam grades) are significantly better compared to the previous semester (e.g., summer semester vs. winter semester).
There are three exams each semester, and the grades are scored from 1 (best mark) to 5 (fail). There are about 24 students that take the exam each time.
What is the right test to use, in order to assess that the marks from the summer semester are significantly better than those from winter semester, considering 3 exams per semester?
(I would like to run the test in R, so if someone happens to know how it's called in R that would be perfect. But I think I can find that out myself.)
Background: I would like to apply for a teaching award. Although marks are probably not a good test of teaching performance if the course design improved, I would like to provide the statistical results as a indication of the merit of my nomination along with the student feedback from the instructor evaluation questionnaire.
The students are different each semester (except possibly for those who fail multiple times). The instructor is different (I am the second instructor). The test is the same. Yes, the difference in the capabilities of the students is a potential confounding factor. I would like to run the test anyway and perhaps I can state that its the difference in the set of students in the classes is not a major factor affecting the difference in the distribution of sources and average scores.