tax-transfer payments - grade transfers

I came across this quote yesterday in my reading of the forthcoming "Common Sense Economics":

"To see the negative effect of almost any transfer policy on productive effort, consider the reaction of students if a professor announces at the beginning of the term that the grading policy for the class will redistribute the points earned on the exams so that no one will receive less than a C. Under this plan, students who earned A grades by scoring an average of 90 percent or higher on the exams would have to give up enough of their points to bring up the average of those who would otherwise get Ds and Fs. And, of course, the B students would also have to contribute some of their points as well, although not as many, in order to achieve a more equal grade distribution.
Does anyone doubt that the students who would have made As and Bs will study less hard when their extra effort is "taxed" to provide benefits to others? And so would the students who would have made Cs and Ds, since the penalty they paid for less effort would be cushioned by point transfers they would lose if they earned more points on their own.
The same logic applies even to those who would have made Fs, although they probably weren't doind very much studying anyway. Predictably, the outcome will be less studying, and overall achievement will decline. The impact of tax-transfer schemes will be similar: less work effort and lower overall income levels."

I'm itching to offer at least one quiz in my economics course this fall on the terms described above, so that the results could be demonstrated to class and effects of redistribution explained!