In some cases it works (beyond the multiple choice quizzes). In the algorithm courses I took, you have to implement a algorithm, and input a number that proves

In some cases it works (beyond the multiple choice quizzes). In the algorithm courses I took, you have to implement a algorithm, and input a number that proves the implementation is correct. For example, on a graph with, say, 500,000 nodes, what are the sizes of the five largest strongly connected components. This is impossible to guess. I also did a course with peer grading of one assignment (the Financial Markets course from Yale). It actually worked surprisingly well. You asses 5 other students' 300-word summary of a paper (based on 3 fixed questions). I didn't think it would work, but I've changed my mind. Mind you, cheating is still a problem (e.g. somebody posts the correct answer online). And, an even bigger problem is proving that you completed the course, not somebody else.