[Catphish]

This is true where I work too (in math/stats). The student evaluation form and the value it is given is one of the the worst culprits in my opinion. If you want a chance at tenure and want to please the dean and the chairman then you better be getting great evaluations. Good luck getting such evaluations if you make your class too challenging. You might get a few good ones but mostly you’ll be raked over the coals by students who otherwise expect to get at least a B+ without much effort. You should teach well and prepare but making your class easy is the main ingredient in getting good evaluations. This is true for online evaluations (i.e. ratemyprofessors) as well and though few will admit it most look and most care.

[The Truth Will Make You Free]

Good luck getting such evaluations if you make your class too challenging.

Exactly. I taught in a university for a few years mid-career. After the first semester I was called in and told my Student Opinion Survey results were bringing down the department's average and I needed to improve or go. My mistakes were that I assumed the students wanted to learn and I taught at too high a level. I did have one brilliant student with a photographic memory tell me that my course was the only one in which he actually learned something.

[Vigilanteman]

I've often felt that student evaluations should be given no sooner than one year after a student graduates. Some 30 years later, I remember the best and worst professors. The average ones, not so much.

The best were the best not because they gave easy grades, but because they gave life lessons which I still find useful.