[2] Young Helen Keller, deafblind and mute since infancy due to a severe illness, is frustrated and angry by her inability to communicate and subject to frequent uncontrollable outbursts.

[4] For the dining room battle scene, in which Anne tries to teach Helen proper table manners, both Bancroft and Duke wore padding beneath their costumes to prevent serious bruising during the intense physical skirmish.

In his review in The New York Times, Bosley Crowther wrote: The absolutely tremendous and unforgettable display of physically powerful acting that Anne Bancroft and Patty Duke put on in William Gibson's stage play The Miracle Worker is repeated by them in the film ...

But because the physical encounters between the two ... seem to be more frequent and prolonged than they were in the play and are shown in close-ups, which dump the passion and violence right into your lap, the sheer rough-and-tumble of the drama becomes more dominant than it was on the stage ...

Patty Duke and Anne Bancroft spark off each other with a violence and emotional honesty rarely seen in the cinema, lighting up each other's loneliness, vulnerability, and plain fear.

What is in fact astonishing is the way that, while constructing a piece of very carefully directed and intelligently written melodrama, Penn manages to avoid sentimentality or even undue optimism about the value of Helen's education, and the way he achieves such a feeling of raw spontaneity in the acting.