If you are a professor on the semester system, you have probably just finished administering your first midterm for the spring, or are about to.
I used to go for long evening midterms and a long final (2 hrs each), and decided these were a nightmare to schedule and a nightmare to grade. After every exam, I would just lose the will to live with all the grading, and I would fall behind on all my other work, plus there is always someone who had to skip the exam for whatever reason, so I often had to administer and proctor make-up exams.
I have recently switched to more frequent exams — three in-class midterms and a final, 50 min each — and my will to live has been holding fairly steady during grading. The students love the higher exam frequency, as they get info on how they are doing more often and their final grade is not so strongly affected by any individual midterm, which alleviates stress. Also, as most professors at my school like to give two midterms, students get swamped during certain weeks as all exams fall at the same time; with three instead of two midterms, we are off-cycle with the other exams and students have a little more time to prepare.
I used to do weekly quizzes, but that simply ends up being too much grading for comparatively little gain. If the students know the quizzes carry very little weight, they are usually not overly compelled to study just for the quizzes. Those who study for the quizzes tend to study and do well anyway. I could make quizzes carry more weight, but then they become like exams, so why have full midterms and not just quizzes in that case?
Anyway, so far an exam about every 4 weeks (or every 3 HW assignments) seems to work well; it provides a balance between the exams being short enough to be done in class and not be too painful to grade, frequent enough to give plenty of feedback to students, yet each is long enough to give meaningful info on the student’s mastery of the material.
I have a confession — I actually quite enjoy creating problem sets, especially for exams and projects. That’s a pretty cool and creative part of the job. For undergrads, I don’t go too crazy with creating original homework because undergrads like to use the textbook in order to feel they have gotten their money’s worth (also to copy the solutions of others); when I assign textbook problems, I explain to students that the homework carries very little weight and is primarily for their benefit, to help them practice, and then the HW does get graded pretty liberally. In some classes it makes sense to have a project component or a programming assignment, which are fun for me to create and for the students to do, and these carry more weight. For graduate students, I have original homework problems and projects, and more often take-home exams over in-class ones. Grad courses are fun as you get to work with examples that are not quite well-behaved mathematically, and with a little programming you can get great insight into some nontrivial but highly instructive problems… But I can really get creative with exam problems, make them instructive and interesting as well as an assessment tool.
I would say a test is of optimal difficulty if the average is 70-80%. There are variations from class to class, but this has generally held, with perhaps an occasional one in the 60-70% range. When I design, I plan for the 1:3 ratio of the times needed to take the test by me and the students, i.e. I need to be able to do it about 15-16 min for a 50 min exam. In an occasional class, I have had to go with a 1:5 ratio, but luckily not too often.
How do you test your students? What are some aspects of exam creation/administration/grading that you particularly like or dislike? How are the tests in the biomedical sciences? How about the social sciences or humanities?