[C4stor]

But the integration by parts article still starts with a very simple sentence, and has a nice colored graphic for comprehension. This is a clear example of "simple and accessible".

It quickly helps forging an intuition of the new concept, using phrases like "Thus integration by parts may be thought of as deriving the area of the blue region from the area of rectangles and that of the red region." which are not very mathematicallish.

All the while, it's a good article for maths people.

Once again, in a great article, what should be simple and explained is not prior knowledge, but the new concept introduced.