Final answer:
The first word spelled into Helen Keller's hand by Miss Sullivan was 'doll,' but Helen Keller's significant realization came when 'water' was spelled into her hand as she felt the water flowing over it.
Step-by-step explanation:
The first word that Miss Sullivan spelled into Helen Keller's hand was doll. However, one of the most profound moments recounted by Helen Keller herself was when Miss Sullivan spelled the word water into her hand as the cool stream ran over it, which was when she realized the concept that everything had a name.
This realization was a significant turning point in Helen Keller's education and her understanding of the world around her. The way Keller's teacher introduced her to this concept was by physically spelling out the letters into her hand, which was the foundational method she used to learn language.