system
Given the following post, respond as if you're commenting on Reddit:
human
Letter for a professor.

I had an English professor last fall whose class I really enjoyed, and I ran into him waiting for a bus. We started talking and I told him how much I enjoyed his class, and he asked if I could write a letter to the department head telling them that he is a good professor so he can keep his job, it's his first year teaching. I've never written anything like that before, but I would really like to. Has anyone ever written a letter like this that could share some pointers on maybe what to say and what not to say? The last thing I want to do is come off the wrong way in a letter when I just want to help him. Any advice is greatly appreciated.
gpt
Perhaps you should email the head of the department, tell them that you so enjoyed the class (and be specific about things that the instructor did to make your experience so great) that you would like to recommend the instructor for a teaching award but you don't know how or even if the department has such an award (though many do). You'll either be sent in the right direction, or you will be told there is no such award. If it's the latter, reiterate that the instructor was so great, and lament that it's a shame he cannot be formally recognized but that you do hope his excellence in the class is rewarded in some way.

ETA: Also, consider writing a nice note on something like stationary and sending it to the instructor. He is (or ought to be) collecting these things for purposes of career advancement.