Which teacher's ideas strongly influenced Georgia O'Keeffe's shift toward abstraction?

Arthur Wesley Dow strongly influenced Georgia O'Keeffe's shift toward abstraction. O'Keeffe studied with Dow at Columbia University Teachers College in New York beginning in 1914, and his approach changed how she thought about making art.

Dow emphasized the organized use of line, color, and tone rather than faithful imitation of visible objects. This approach gave O'Keeffe a framework for making expressive compositions from simplified forms. Her later abstract drawings and watercolors helped lead to the paintings for which she became famous.

O'Keeffe had already received conventional art training at the School of the Art Institute of Chicago and the Art Students League of New York. She became dissatisfied with academic methods, so Dow's emphasis on design offered a major alternative.

Robert Henri and William Merritt Chase were important figures in American art education, but they were not the teacher most directly associated with O'Keeffe's decisive move toward abstraction. Dow's influence is the specific answer.