I'm really big into science.  It's my favorite of all the STEM fields, although math is a close second.
what is STEM fields? I have never heard about it
STEM is an acronym for Science, Technology, Engineering, and Math.  Back in the day, it used to be called METS.
I see. I love math, at college I studied calculus, and I loved it
I never made it past calculus in high school.  I especially liked the parts that dealt with calculations of volumes of rotating graphs and areas under a curve.
Well, when you are studying calculus is the same thing, you want to know about the areas too
I wish I had spend more time with differential calculus, because a a pilot now, there's a lot of math that has to do with rates of change.
why did not you spend more time with differential calculus? 
I think it had more to do with the teacher.  He just had a thing about quantities and areas under curves and what not.
I see, a good teacher helps us to have a good education