Summary: Students who have never taken a particular course often can get "credit by exam". However, it's extremely common for credit by exam to be disallowed to students who have previously taken and failed a course. For example, see the policy of the University of Mary Washington. Is there pedagogical reason for that different treatment of students who never took class vs failed the same class?
In my own experience, I have seen way too many undergraduate students that I thought could have passed if they had had two or three more weeks to study. They seem like an ideal use case for credit by exam:
- Fail the course.
- Get some extra tutoring over the break.
- Sit credit by exam at the start of the next semester and earn passing marks.
This argument applies especially for lower-division undergraduate courses (e.g. Chemistry I, Introduction to Psychology, Survey of US History, etc.) that are especially commonly offered in credit by exam format. These courses typically require a relatively shallow level of mastery of a wide body of knowledge, which can be easier to test for on exams rather than projects or term papers.
Question: Are there pedagogical reasons for not allowing students who have previously failed a course to sit a credit by exam examination while allowing students who have never taken the course to do so?
One obvious argument could be that credit by exam assessments may not be as rigorous as actually completing the full course (attending all lectures, completing all homework, participating in class discussions, etc.). If that is true, then I really wonder why credit by exam should even be offered at all - it doesn't make sense to single out some students who are allowed to follow an abbreviated path and others who are not.
To be clear, I'm not asking for a link to your institution's credit by exam policy nor am I looking for counterexamples (universities where students can get credit by exam for courses they have previously taken and failed). What I'm looking for is a pedagogical argument for having this policy. In other words, if I was in charge of setting credit by exam policy at my institution (I'm not), why would I want to go to the trouble of barring certain students from taking advantage of it rather than just saying that anyone who can pass the exams deserves the credit?
In response to comments, I am asking from the perspective of the USA.
The 2 camps: I've noticed a battle raging here in the US between camps over whether degrees ought to be about competence or completion. The competency camp claims that requiring formal study is unfair to those who can't afford to "go to college" but could learn on their own or at low-cost, unaccredited community learning centers. The completionist camp argues that without the "these hallowed halls" experience (being fed scraps of learning by social superiors, microwaving another bowl of ramen before rushing to another 7 AM lecture in an unheated lecture hall in the middle of a New England snowstorm, etc.), degrees are meaningless.
There are also curriculum control issues: In competency models, curricula are set by administrators, accreditors, or regulators and professors are expected to "teach to the test". On the other hand, competency supporters will respond that in the completion model, there is no guarantee that the professor will adhere to any standards at all.
We're getting a bit far from the original question, but a big reason for the competence model is the rampant credentialism we've seen here. With professions increasingly requiring a bachelor's degree or even a master's just to get in at the ground level, there are widespread calls to give these degrees to anyone who can demonstrate that they can do the job. Whether this is good or bad is beyond the scope of this question.