19. This was a trick question.  It requires several kinds of learning, including understanding and application of concepts, procedures, and principles.

    20. As stated, this could be memorization or understanding.  It is ambiguous.

    21. While this may seem like primarily a physical skill, it also requires some memorization and some procedure application.  If unexpected problems arise, it would also entail some understanding and application of principles.

    22. Technically, this is application of a concept, because all $1 bills are different in small ways (such as serial number and crispness).  But in reality it is more of a memorization task, because all the instances look almost identical to each other.

    23. While the word "identify" is usually associated with application of a concept, this requires only memorization.