I teach two very large sections of biochemistry (150 students x 2 sections). In an effort to mitigate the rampant cheating that occurs, I create multiple test banks and ask canvas to choose a certain number of questions from each bank. I make all the banks sufficiently large so that the system has a good selection of questions to choose from so the students do not end up with many overlapping questions. However, I'm noticing that canvas will select a set number of questions and vary their order between students (in both classes) but the number of questions asked is not equal to the total number of questions in the bank(s). For instance, I first made one large bank containing 225 questions, only a fraction of which were assigned to the students. The next time, I made 4-5 smaller banks containing a similar total of questions and I am still facing the same problem. The variety of questions I put in is being thwarted somehow to a subset which actually gets assigned to students. Am I doing something incorrect? I've even had instances where questions are duplicated (not in the bank but on student quizzes). Help!
To summarize: even thought I'm making an effort to thwart too many overlapping questions, its still happening.