Cipher in the Snow (1974)

Asking to leave a school bus, Cliff, a young teenager, collapses and dies in the snow near the roadside. His math teacher is asked to notify the parents and then write a short obituary. This task is difficult, for although he was Cliff's favorite teacher and had the most interaction of any at the school, he barely knew him. In unraveling the mystery of the untimely death, he finds that Cliff was shy, lonely, and ostracized, being slowly reduced to nothing, a zero (cipher). He vows to not let this happen to others.