I remember when I was a biology major in the late '90s, my professors tried to explain the controversy of 5 kingdoms vs 3 domains vs 3 ecological categories, etc. I think the science was recent enough that it wasn't yet clear how to teach it.

The same goes for the issue of antibiotic resistance and horizontal gene transfer. My teachers in med school knew about it, but I don't think they knew how to convey the implications. This is life-and-death stuff I would have liked to have a better handle on, even last summer as I personally battled multi-drug-resistant urosepsis.