@cue7 Those are great questions. I am interested in the answers too. I do know that D has taken 21 credits in 3 schools and has a major in SEAS (CS), a minor in CAS (math), and a minor in Wharton 1/2 done (Stat) and all courses have been taught by professors. Assistants often lead recitation, but are not allowed to teach new material.
Maybe post docs and teaching assistants teach at Drexel or Temple for experience? Idk.
Another example of a Penn research opportunity is that D had a 4 person group project for a class and the professor liked their paper. He contacted the 4 students in the group and asked if they would be interested in further developing the idea into a research paper.
He offered to oversee their effort and provide significant funding that he has available to pay for the additional data collection that would be needed to support the paper. I don’t know if this happens often at Penn, but it happened to D.
I know every student doesn’t get an amazing research experience. However, the opportunities are there for students with demonstrated skills and abilities, and there are a lot of students like that at Penn.