The Great Terror. J.Arch Getty et al. This only one required textbook. This does not mean that my goal is just to make you read this one book. Robert Service gives a good standard account of the twentieth century Russian history but it can not give you a broad vision of the subject - as no any other single book.
Additional reading is thus a necessary complement.
However, the most important in understanding history is seeing it and hearing it. You will apply your uncommon knowledge in writing your research papers. All grading is cumulative. I believe, however, that a better strategy is to earn 30 points during the semester, write a very good paper, and get A honoris causa - without taking part in the otherwise inevitable lottery of the final exam. In compliance with what has been said above, research paper is the most important part of the course work.