During a 36 year period, I had the privilege of teaching students at three large public universities: University of Nebraska, University of Hawaii, and University of Illinois.
Included in the many classes I taught were the following:
Upper division: Electricity & Magnetism, Astronomical Instrumentation, and Galaxies & Cosmology.
Lower division Introductory-level General Astronomy designed to meet undergraduate science requirements. I estimate the total enrollment in all of these classes to be well over 5,000 students.
Especially important to me were the 11 consecutive years (1989-2000) I taught the Galaxies & Cosmology graduate course at the University of Illinois. Advanced undergraduate students were admitted to the class with my permission.