All students are graded at some point. On the other hand, professors seem to have avoided that part of the study. Of course I do not propose that they would be graded on the same way as students, but grading could bring some very positive effects. I thought of grading more like a reference for professors, so they would know which lecture is interesting for students or are the students more happy than last year (or if they wont a pay rise) etc. In case of bad lecturer it would also provide a reference for the students to demand a change (if some professor is poorly graded for several years...). The grading system could remain the same, what it is important is that mechanism for grading is easily accessible to students (iPhone, android apps) and that it is anonymous. Students could grade each lecture (from the mobile apps in the break...) or lecturer in general. Also the study board of the ETH would better know students from which department are generally happier with their lecturers and which are a bit less happy, so they could act accordingly.