CHUCK JONES: The Dot and the Line (1965)

From Wikipedia...

The Dot and the Line: A Romance in Lower Mathematics (ISBN 1-58717-066-3) is a book written and illustrated by Norton Juster, first published by Random House in 1963. The title is a reference to Flatland: A Romance of Many Dimensions by Edwin Abbott Abbott.

In 1965, famed animator Chuck Jones and the MGM Animation/Visual Arts studio adapted The Dot and the Line into a 10-minute animated short film for Metro-Goldwyn-Mayer, narrated by Robert Morley. 

The Dot and the Line won the 1965 Academy Award for Animated Short Film. Five years later, Jones turned another Juster book into an animated feature film, The Phantom Tollbooth.