Alon Bement taught Georgia O'Keeffe at the University of Virginia in the early 1910s.
O'Keeffe worked at the University of Virginia as a teaching assistant and instructor during the summers from 1912 through 1914. Bement, who was connected with the Teachers College art-education program, introduced her to ideas about teaching art through fundamental principles rather than simple imitation.
Bement's influence helped lead O'Keeffe to Arthur Wesley Dow, whose approach emphasized composition, line, color, and personal expression. O'Keeffe later credited Dow's ideas with giving her a way to make images that expressed her own response rather than merely reproducing what she saw.
William Merritt Chase was a different teacher from her earlier studies at the Art Students League. Arthur Wesley Dow also became an important influence, but he was not the teacher named in this question.