One fundamental difference between grades and assessments is that the former is used to motivate students. In fact, we've created a whole industry that depends on this kind of motivation, from accreditation downwards to the classroom: a kind of "do this or else" mentality. Surely this can't be ideal. I appreciate the requirements of state education to more or less force kids out of their beds in the morning, onto busses, and subject themselves to ideas that hurt to absorb. But higher education? Especially in the liberal arts, we talk about general goals like creating life-long learners and such. How does that square with our methods of delivery?
That discussion comes back to the topic of noncognitive traits in learners: how motivated is Tatiana to learn computer programming? For a motivated learner, assessments are better than grades because they get straight to the point of "how well am I doing?" without the coercive baggage that's inherited from elementary school. This is, by the way, an argument for detailed reports in assessments as well. The more gooey they become, the more they resemble grades and the less useful they are. Compare:
Tatiana sees her score of 79% on the C++ test and concludes that she is doing okay, but not excelling.Only the second of these is actionable--Tatiana can increase her skills by practicing with pointers, getting tutoring, reading what others have to say about the subject. Learning is about details, and assessments should be too. With the ubiquity of modern information systems, keeping track of details isn't a problem--we just have bad habits left over from the grade school mentality of reducing a semester's work to a single letter. It's absurd, if you think about it.
Tatiana reads her C++ assessment and sees that while basic control structures are second nature to her, she really doesn't understand pointers.
Can we find another way to motivate students? I don't know, but I don't think we're really trying. I can imagine a culture that fosters a more inquisitive approach to self-improvement, but don't know how that might be engineered. And yet, we don't really want to produce graduates who only perform in order to get the pellet in a Skinner box, do we? I think the first step is to start to assess certain noncognitive traits, and bring them into the curriculum (and not just in orientation course). I'm not saying that all students lack self-motivation, of course. We have and value the go-getters in class who drive classroom discussions, ask for new things to read, and always come for help when they don't understand. How do we harness that energy to help pull along students who aren't so energetic in their learning practice?
Until such a motivation exists, it's probably best to keep grades to push students along and keep the political pressure off assessments. It's very convenient for the Assessment Director to not have to worry about the kind of scrutiny that the registrar requires. But it is a capitulation of sorts.