One of my all-time favorite shorter stories is “Flowers for Algernon” by Daniel Keyes. They made it into a film called Charly in 1968 starring Cliff Robertson and Claire Bloom. From wikipedia:
Charly…tells the fictional story of a mentally challenged bakery worker who is the subject of an experiment to increase human intelligence.
Here’s the film in a convenient YouTube Playlist (plays all parts)…
[via Divers and Sundry]