The exams have not worked as well as I would have liked. The change I made this semester to release the essay questions prior to the exam and to ban cheat sheets did not fix the problem.
The problem from past exams where I disclosed the general topic area of the essay and allowed cheat sheets was that students told me everything they knew about the topic but did not answer the question asked. I had put this down to students trying to prepare an essay answer on their cheat sheets and then copying out in the exam no matter what the question was. This year's performance suggests that I had drawn the wrong conclusion.
This year, again, students wrote everything they knew about the topic without answering the question. The problem appears to be that students do not know how to answer questions.
To address this in future semesters I intend to devote class time in lectures and in tutorials on how to answer essay questions in assignments and in exams.