I have a statistics question as well. I want to compare two sets of data with different proportions. For example, A teacher gives As, Bs, Cs, and Ds in a particular class for two different years, and states that he gave a similar proportion of each grade both years.

If I wanted to show that the grade breakdown's difference between the two years was statistically significant, would I use a Chi Square test? If not, what test would I use?