I agree with Howard. It is most unusual in education for the purpose of teaching and learning that the outcome is some people who cannot be identified may have learned some things but we don't know who they are.
It is far more common in my experience, particularly as I have just gone through exam results for an intense scrutiny of who learned what and who did not.
I am of course using "pass exams" as a proxy for learning which is not always an exact relationship.