I did my Master's at a top Canadian university in 1992. I was T.A. for the 4th-year graphics course, one of the "big three" at that school.
Each term we had about 25 students, 5 or 6 of whom were really good.
I went to industry for a decade, then decided my life was too easy.
I finished my Ph.D. at the same school in 2007. I was T.A. again for the 4th-year graphics course.
Each term we had about 50 students, 5 or 6 of whom were really good.
The "gene pool" of good, motivated students didn't change from 1992 to 2007, the profs were every bit as good both in research and teaching skill. The only "improvement" was the pool of fee-paying, half-subsidized students taking the course. The population of the province sure didn't double during the time, but the 1990's drive to get "more technical people" sure doubled the intake. The 5th year of high school was also trimmed back.
I knew faculty who quit for industry rather than teach remedial high-school math.
"Computer Science: because your Mom told you to!" was the headline of a poster seen outside the student society door... hits the nail on the head.
Biology grows on you.