Music to a Professor's Ear

I'm tooting my own horn here, but comments like these validate my approach to teaching:

Beside anything, one thing is clear. I learned more stuff on Economics from your [class] than any other economics courses. I thank you for teaching though this course may appear as the lowest grade in my transcript. Hope you to have good summer.

Rigorous instruction and tough grading aren't popular, but they produce better students - who will go on to make up the difference by having better grades in future classes and perform better in professional environments.