This course will have 3 tests and a final exam.
In the old days I simply dropped the lowest of the three test scores, but then I noticed that many students who did well enough on the first two tests would blow off the third test, and would not learn the material towards the end of the course very well. So I then decided to drop only the lowest of the first two test scores. And then the same thing seemed to happen with the second test: some students who did well on the first test would blow off the second test. And their learning would suffer.
My final remedy was to drop the lowest of the first two test scores provided that the followup test score was higher (rewarding improvement). But with any upside, there is usually a downside. Some one could do pretty well on the first test, just a bit less well on the second test, and do really poorly on the third test and their average will then be lower if the second test is dropped. Yes. The down side is that this rule penalizes doing worse at the end than at the beginning. Life is not fair and no matter how you make rules, they won't quite work for every situation.
I reserve the right to bend the rules under extenuating circumstances if it will be in the student's benefit and if merited.