The Miracle Worker tracks the progress of Annie Sullivan as she attempts to teach Helen Keller who was left blind and deaf after an illness as a baby. Annie has herself had many operations for her own blindness and has been taught at The Perkins' Institute for the Blind. She knows little of the Keller family and they know nothing of her or her difficult childhood as she and her brother, Jimmie, were orphaned and Jimmie died. When Annie came to the institute she could not even write her name and now she will leave a governess. Mr Anagnos tries to encourage Annie, describing Helen as "a little safe, locked, that no one can open" and he's hopeful that Annie can help her because "Perhaps there is a treasure inside."
Annie knows that she is a stubborn young woman and, Mr Anagnos points out to her that she lacks tact. She receives a gift now that she is to leave the institute and is moved by the gesture. She tries to express her appreciation and she credits Mr Anagnos with everything that she has accomplished, especially as she is just an "ignorant, opinionated girl." (Act 1)