Mark Twain was the first person to refer to Anne Sullivan as "the miracle worker". Twain was a friend of Helen Keller.
Although Patty Duke had been playing Helen Keller in the play for more than a year, she almost didn't get the part in the film adaptation. The studio felt that being a teenager, she looked too old to play a seven-year-old. However, they decided to use Duke after deciding to use Anne Bancroft, who played Duke's original Annie Sullivan in the play.
Patty Duke later played Annie Sullivan (with Melissa Gilbert as Helen Keller) in the TV production (The Miracle Worker (1979)).
When Patty Duke won the Oscar® for Best Supporting Actress, she became the youngest actor to win a competitive Academy Award®. This record stood for 11 years until Tatum O'Neal broke it in 1974 for her role in Paper Moon (1973).
The play originally was produced as Playhouse 90 (1956), The Miracle Worker (1957), broadcast on February 7, 1957, starring Teresa Wright as Annie Sullivan, Patty McCormack as Helen Keller, Burl Ives as Captain Keller, Katharine Bard as Katie Keller, and directed by Arthur Penn, who also directed both the TV and film versions.