[muawiyah]

Calculus I has only one difficulty ~ the questions ~ they are all hard but that's usually because the instructors failed to get across to the students how simple they were.

The "it is intuitively obvious" statement does not work at this level as a substitute for "discussion" in the classroom.

[RSmithOpt]

If one has difficulty in algebra and does not understand its applications in the real world, then, calculus is inherently that much more difficult.

I always was taught 1/2 of the 3 courses I had in calculus from a statistical view point, which I loathed...I had to poke around in higher level engineering (structural and soil mechanics) books in the library to get a good handle on it and appreciate its applications.