These students were in a Nguyen situation.
Intro to Chemistry doesn't sound like something that should be taught in college

I heard Intro to Math was a real bear.
You laugh, but at my college (a four year regional university), "college algebra" is the minimum math requirement, and it's considered one of the more difficult courses in the university. I hear stories all the time from advisors in other deparments -- e.g, Journalism, Theater, Visual Arts, Music -- about students who fail this class three times and have to petition to get a fourth try. All over a class that probably would have been considered remedial when all of us were in school. It still blows my mind to think about this.
In other words, don't just assume that all high school graduates have minimally proficient math and science skills. A disturbingly large proportion don't.
Ahhh, College Algebra.
I was supposed to take College Algebra because of a deficit in my HS math curriculum...and by that I mean I flunked a semester of Algebra II my senior year. Yes, I'm mathematically re###ed and I'm aware of that. So my HS math teacher said if I got a C over the 2nd semester that it would average out and I'd get credit for a full year. And trust me, I had done the research to make sure what I needed to avoid taking ANY math class in college.
Anyway, I never noticed until my senior year in college that my HS transcripts were a 1/2 a math credit short because my teacher was a spiteful little pr*ck and lied to me about getting full credit. I decided to follow the real Homer Simpson's advice and just crawl under a pile of coats and hope everything turned out ok. I would have literally dropped out rather than take College Algebra. Luckily, the History department didn't communicate with the registrar or something and everything turned out honky dory. Except I learned far too late how useless a History degree is.
tl;dr -- I actually shouldn't have my college degree.
Exact opposite here. Took AP Calculus in senior year of HS. Teacher told us we could have our parents submit some kind of permission slip and for $50 we could have the course applied to the local state school for their math requirements. Calc just didn't click with me after the first couple of months. Got totally lost in November and was deep in the weeds by Christmas. Tried my best, worked with the teacher, but just couldn't get through it. Bombed the course pretty bad, but, most of my class did, too. For the "honors" class we were all in deep over our heads in this stuff, and it was the same teacher we had in junior year for pre-calc, so he knew where we were all starting from.
Anyway, teacher tried his best all year, too. A couple kids were standouts who got it but most of us were dead in the water. End of senior year, he makes a deal with the class... just
try on the AP test (which can be used to get out of having to retake courses in college) and he'll give us a C in the course no matter what our score is. Get a 5/5, get an A, get a 4/5, get at least a B, but get a 1, 2 or 3 and he'll bump our grade up to a C if it's below that. So, like a free shot at passing for just taking the AP test. I took it. Bombed it. 1 out of 5, the lowest possible score. Teacher held up his end of the bargain, though, and passed me with a 70.
Fast forward to college. Went to a big-name out-of-state private university. Applied as a new student, show up on my first day and I get handed a transcript with what college courses carried over from high school for credit based on my AP test scores. Had the ones I expected, AP English, AP History, aced those tests. Then I look and AP Calculus is on there. I look again, and, for some reason I'm classified as a "transfer student".
Turns out that $50 that I forgot about at the beginning of senior year meant that even though I bombed the AP test, my 70 "C" counted for college credit at my local state school. Completely unbeknownst to me, the local state school had somehow sent that 70 to my out-of-state university as transfer credits. Since it was a full-year course in HS, it counted for 2 semesters. Calc I & Calc II. 8.0 credits total. Throwing in the extra stuff and it made me able to skip a whole year of college. Didn't have to take any "hard math" courses because Calc II fulfilled the requirement.
tl;dr: Nice Guy calc teacher saved me a year of college despite my F because of paperwork magic that I had no idea happened.