Hello! You asked about Annie Sullivan and her greatest strengths in dealing with Helen Keller. After losing her sight and hearing because of a childhood fever, Helen Keller is almost institutionalized. However, when the Kellers contact the Perkins Institute For The Blind in Boston, the institute sends them Annie Sullivan, who becomes Helen's teacher.
When Annie realizes that the child has been spoiled and allowed to run the household like a little tyrant, she reasons that she must first teach Helen obedience if she wants to teach Helen how to read and write.
I saw clearly that it was useless to try to teach her language or anything else until she learned to obey me. I have thought about it a great deal, and the more I think, the more certain I am that obedience is the gateway through which knowledge, yes, and love, too, enter the mind of the child.
Not only is Annie patient and determined in her dealings with Helen, she also utilizes Helen's three remaining senses of touch, taste and smell to teach Helen. She also teaches Helen to have self-control, as she herself, who is blind and has been institutionalized, has had to learn. Here is an excerpt of a letter she writes to her patron at the Institute For The Blind, Sophia Hopkins:
...I thank you from the bottom of my heart for the mother-love you gave me when I was a lonely, troublesome schoolgirl, whose thoughtlessness must have caused you no end of anxiety...
...There have been murder and treason and arson in my heart; but they haven't got out, thanks to the sharpness of my teeth which have often stood guard over my tongue...
Annie Sullivan's creative approach to teaching Helen contributed greatly to her success with her student. She adapted the lessons to Helen, not the other way around. In other words, she tailored the curriculum to Helen's needs.
Apparently, children learn language more quickly when they are free to move about among objects that interest them. They absorb words and knowledge simultaneously. In the class-room they cease to be actors in the drama, they sit and watch the teacher doing something with her mouth which does not excite their curiosity particularly. Passivity does not stimulate interest or mental energy. The child learns eagerly what, he wants to know, and indifferently what, you want him to know.
Annie Sullivan used what she had learned from Dr. Alexander Graham Bell with Helen. From Dr. Bell, Helen learned how to deliver proper, constructive criticism to a student. He was also unfailingly courteous in his demeanor.
He imparted knowledge with a beautiful courtesy that made one proud to sit at his feet and learn.
If he wished to criticize me, and he often did, he began by pointing out something good I had done in another direction.
So, you can see that Annie's strengths as a teacher were her patience, determination, creative approach to teaching, and her knowledge of how to properly offer constructive criticism.
Below are two links you will find immensely useful as you study Annie Sullivan. Be sure to read her letters in full. Thanks for the question!