This has got to be the most ridiculous thing I have ever hear of (no offense)! Aikido is not about pencil pushing in a classroom. There grades should come from the mat, e.g., how they perform, how they carry themselves, their ki excercises, etc. But if you must give written exam for university procedures sake, here is my suggestion.
I take "elementary" to be "beginner of beginners" so, if this is the case, they should not be answering theoretical questions of depth at their level. Start them out on perhaps terminology questions such as: What is mushin? What is the importance of maai? Name 8 (or how many you want) ki exercises. Who is the founder of Aikido? In a brief description, what is aikido? What country did aikido originate? What is ki? Name the postion of high and low on the mat. What erm means "senior student"? What does kohai mean? Name the 5 postions of the bokken. etc etc.
Yoiu get the idea. These are some basic questions that I would ask at the end of a semester for a final, because some of your students could be new and you have to take that into account that they might need time to learn these.
Your best bet is to devise an exam fitting for each rank to be fair!!!!