There is a difference between a complex subject and a poor instructor for a complex subject.
My organic chem class for chemistry majors had an open book, open note, final. The highest grade, an A, was 41% correct...
The student was enrolled in the Ph.D. program for physics at the time.
The instructor lectured for one week on Grignard reagents. When asked why he didn’t have a question on the test about Grignard reagents his reply was that he had lectured for a week, so everyone would know the material. He was a rookie professor.
True. I bombed Analytic Geometry the 1st go-round. It didn’t help that we had big problems at home with my Mom deathly ill & Dad wouldn’t help with household chores so as eldest child I got to do almost all that. But, the prof just didn’t get through to me, and I was always somewhat “sensitive” to a teacher’s communication skills.
Came back the next semester, better teacher, as much or more work, but also had a friend for a study partner, and Aced it.