It's unfortunate you were in a geographic location and a time that exposed you to poor math teachers.
I was taught calculus in high school, well before university, in Australia in the late 1970s.
Visual analogies such derivatives being tangential rates of change and 2nd derivatives being local curvatures were taught and drawn on the board in the first week of two years of Calc I and Calc II classes that came before leaving high school to attend university.
I was taught calculus in high school, well before university, in Australia in the late 1970s.
Visual analogies such derivatives being tangential rates of change and 2nd derivatives being local curvatures were taught and drawn on the board in the first week of two years of Calc I and Calc II classes that came before leaving high school to attend university.