Professors have to be so careful in this age of political correctness (PC). Life just isn't as much fun as it used to be. Students have to be given written notice, at the start of of a course, of the nature and dates of any assessment. This immediately eliminates the joys of waking them up the class with a "snap quiz"! Unless you want to hear from the Dean.
One of the few weapons left in our arsenal is the final exam. - assuming we're allowed to have one. Of course, we have to supply "practice exams."; solutions to previous, related, exams.; and almost everything except the questions themselves. Actually, I did hear of a course in another discipline where the students were given a set of x questions in advance, and told that a subset, y in number, of them would constitute the final exam. Sorry - I just can't go there.
When I was an undergrad. math. student, in a different educational system, courses went for the whole academic year; there were no term-tests; "assignments" didn't count to the final grade; and then at the end of the year each course had two final exams. - Paper A and Paper B. Three hours each - sudden death - just like double-overtime in a Stanley Cup final. Oh yes, those were the days!