but you did not take calculus in elementary school.
It isn't that difficult.
calculus in elementary school - Google Search
Calculus in 4th grade?
A while ago I discovered an interesting web site,
Berkeley Science Books, that publishes a set of very comprehensive Ebooks called "Calculus Without Tears." Author Will Flannery has a pretty detailed explanation on the home page of his web-site of why he thinks Calculus can be taught in elementary school. His view is that Calculus in college is bogged down with lots of theory; if you change the focus of Calculus to application first and theory later, and if you teach the fundamentals of Calculus that don't require algebra, trigonometry, or geometry (except for the formula for the area of a rectangle) then you can teach Calculus to 4th graders. Flannery sees the motivation for all of mathematics, beyond basic arithmetic, to be physics, and the building basics - derivatives, integrals, and differential equations, which are fundamental to physics and to Calculus - can be taught to those with no mathematical sophistication.
I was fortunate enough to be given the opportunity to learn calculus at an early age. Our regular teacher had taken ill and we were being taught by the deputy principle instead who was probably one of the best teachers I ever had.
He even combined geometry with art by teaching us how to make mosiacs and yes, he taught us calculus too.
Many years later I was talking to the son of friends of mine who said that he was struggling with high school math and he asked if I would tutor him. I asked him what he was having a problem with and he said that it was mostly algebra equations. I pointed out to him that he had been taught how to do the simple arithmetic of a+b and c/d in elementary school so he should ignore those simple parts of the equation and look at the larger problem instead.
A couple of months went by without him ever calling me for a lesson and then I bumped into him again and asked him if he still needed my help. He said no because I had taught him everything he needed to know in that one conversation. He had gone back and looked at those algebra equations in a different light and he was now acing math with straight A's.
In essence that was me passing on the lesson I learned in elementary school from the deputy principle. All math, even calculus, is made up of the same simple principles and it is only the methodology that you are using that is different. Geometry, algebra and calculus are not that difficult to understand and yes, even kids in elementary school can learn how.