Benjamin Samuel Bloom (February 21, 1913 – September 13, 1999) was an American educational psychologist who made contributions to the classification of educational objectives and to the theory of mastery-learning. He also directed a research team which conducted a major investigation into the development of exceptional talent whose results are relevant to the question of eminence, exceptional achievement, and greatness. In 1956, Bloom edited the first volume of Taxonomy of educational objectives: the classification of educational goals, which outlined a classification of learning objectives that has come to be known as Bloom's Taxonomy and remains a foundational and essential element within the educational community as evidenced in the 1981 survey Significant writings that have influenced the curriculum: 1906-1981, by H.G. Shane and the 1994 yearbook of the National Society for the Study of Education. Bloom's Two Sigma problem is also named after him.