The big thing is that vectors seem to be the kind of “shoved into the end of the semester if there’s time after testing” from what I’ve seen. Most of the time, even when I work with calculus students they have no idea what a vector is.

A big thing to is getting them to understand what square roots even really mean. I’ve noticed a lot of students struggle with getting sqrt(x) * sqrt(x) = x, so even just the simple “hey, can you get a negative by taking a number and multiplying by itself?” is often a hurdle cognitively. (A lot of this I suspect has to do with not understanding what multiplication or division really “are” - I usually remediate with the area model)