Bloom's Taxonomy

Throughout the 20th century, educators explored a variety of different ways to make both explicit and implicit the educational objectives taught by teachers within PreK–12 classrooms. In the early 20th century, objectives were referred to as aims or purposes, and in the early 21st century, they evolved into standards. During much of the 20th century, educational reformers who wanted to more clearly describe what teachers should teach began to make reference to objectives, which referred to the type of student learning outcomes to be evidenced in U.S. classrooms. One of the most significant representations of those outcomes evolved out of the work of Benjamin Bloom and became known as the taxonomy of educational objectives. Bloom's taxonomy represented a significant reform because it fostered a common vocabulary for thinking about learning goals, it engendered a way to align the educational goals, curriculum, and assessments that are used in schools, and it structured the breadth and depth of the instructional activities and curriculum that teachers provided for students.

Almost all teacher education institutions and most teachers within U.S. classrooms began to think taxonomically about how to describe the learning outcomes that would be taught in their classrooms. Bloom's work was not only in a cognitive taxonomy, but it also constituted a reform in how teachers thought about the questioning process within the classroom. Indeed, the taxonomy was originally structured as a way of helping faculty members think about the different types of test items that could be used to measure student academic growth. Bloom and a group of assessment experts he assembled began their work in 1949 [Page 107]and completed their efforts in 1956 when they published Taxonomy of Educational Objectives: The Classification of Educational Goals, Handbook 1: Cognitive Domain.

Bloom's cognitive taxonomy originally was represented by six different domain levels: (1) knowledge, (2) comprehension, (3) application, (4) analysis, (5) synthesis, and (6) evaluation. All of the Bloom domains focused on the knowledge and cognitive processes. David Krathwohl and some of his associates subsequently focused on the affective domain, which is concerned with student interests, attitudes, and feelings. Anita Harrow developed the psychomotor domains, which deal with a wide variety of motor skills. Bloom's work is most noted for its focus on the cognitive. Bloom became closely associated with the cognitive dimension even though, in subsequent work, he often examined the wide variety of “entry” characteristics (cognitive and affective) that students evidenced when they began their schooling.

Each of Bloom's cognitive domains enabled educators to begin differentiating the type of content being taught as well as the complexity of the content. The domains are particularly useful for educators who are thinking about the questioning process within the classroom, with questions ranging in complexity from lower-order knowledgetype questions to higher-order questions that would require more complex and comprehensive thought. Until Bloom's reformative work surfaced, teachers often asked questions without a structure for thinking about the type of question being asked. Good teachers have always dialogued with their students and questioned them on their understanding of material. Bloom's taxonomy enabled teachers to think in a structured way about how they question students and deliver content. The taxonomy, in both its original and revised versions, helped teachers understand how to enhance and improve instructional delivery by aligning learning objectives with student assessments and by enhancing the learning goals for students in terms of cognitive complexity.

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