I’ve taken courses and exams both ways. In my opinion, Open Book affords students the opportunity to revisit the items learned during classroom and study which allows for better retention of the materials. We want the individual to learn but also be able to know where to look up information on an as needed basis. I’m certain folks here have a plethora of certifications and certificates on various subjects, yet still have to reference materials for guidance and clarification from time to time. I don’t think that’s a bad thing.  Happy Learning, All.