I think that it is helpful to consider the differences between differing assessment practices-- something that Kohn seems to often be on the verge of doing, but never quite gets there. Like Val, I find that I sometimes agree with him, but usually wind up shaking my head and sighing that if only he'd stopped there, I'd have been happy to agree with him and pass his write-up along. But alas...
I digress.
There is a role for formative assessment in shaping learning, and it doesn't foster all of the ills that Kohn ascribes to the practice of assigning values to performance metrics.
Then again, there are not consequences for mistakes in that kind of assessment-- it's merely a matter of seeing how the learning process is coming along, if you will.
Summative assessment, on the other hand, is the kind that evaluates what you have learned, and how well, at some fixed point in time after the learning process has theoretically taken place. This is the one which assigns a "value" such as a letter grade, a certification of some sort, etc. regarding the level of mastery that the student has attained.
The trouble is that many educators and certainly those producing tests and materials have forgotten that this distinction matters at all-- and have hopelessly married the two things together in the world's most hideous shotgun wedding ever.
This is where daily three-question multiple choice "quizzes" that count as 20% of a student's course grade come into things. Because homework is NOT evaluated anymore-- (that would have been "formative" assessment, by the way)-- but note that if you miss anything at all-- that is, if you aren't "perfect" more often than not? You have a D percentage for that portion of your class grade. The SUMMATIVE grade.
See what I mean?
It's not that either thing is awful by itself-- but that BOTH things are ultimately rather important to producing competent and healthy learners who strive for excellence (because it matters in the summative model) but avoid perfectionism (because it's okay to make mistakes during the formative portion of the assessment model).
