I enjoyed my AP Calc BC class in high school, but found the Multivariable course to be dreadful at Duke. I just didn't get it towards the end. Similarly Differential Equations was somewhat of a turnoff.
Then some years later I found MIT's Open Courseware and their DiffEQ and Multivar classes were awesome!
Between the main lectures (in the DiffEQ case recorded almost 20 years ago at this point, and the professor just recently passed away) and then supplemental recitation lectures done by TA's, it really clicked in a way that never did while on campus.
Nowadays there's so much great content on Youtube and other sites (if you can find the good stuff, because there's also a plethora of mediocre ones as well) it almost seems unfair.
Many of the YT comments are along the lines of "Wow thank you so much for explaining it like this; my professor is terrible and made zero sense and I was freaking out until I found this video"
A text without a context is a pretext.