On March 3, 1887, teacher Anne Sullivan met Helen Keller

Helen Keller (1880-1968) and Anne Sullivan (1867-1936)
USPS issued June 27, 1980

20-year-old Anne Sullivan traveled to Ivy Green, Alabama to take over the education of blind and deaf child Helen Keller.  

… [She] began working to socialize her wild, stubborn student and teach her by spelling out words in Keller’s hand. Initially, the finger spelling meant nothing to Keller. However, a breakthrough occurred one day when Sullivan held one of Keller’s hands under water from a pump and spelled out “w-a-t-e-r” in Keller’s palm. Keller went on to learn how to read, write and speak. With Sullivan’s assistance, Keller attended Radcliffe College and graduated with honors in 1904.
Helen Keller meets Anne Sullivan, her teacher and ‘miracle worker’ | March 3, 1887 | HISTORY

Biography | American Foundation for the Blind (afb.org) has an excellent page on Sullivan and Helen Keller.