Bloom's Taxonomy of Educational Objectives is a way of organizing different levels of educational expertise into a tiered system. The tiers are separated into three main groups: skills-based, knowledge-based and affective goals. Educators place each course goal into one of the three groups and then choose the appropriate expertise level.
There are seven levels of expertise within the skills-based goals category, namely perception, set, guided response, mechanism complex overt response, adaptation and organization. Within the knowledge-based goals are six expertise levels: knowledge, comprehension, application, analysis, synthesis and evaluation. The affective goal category has five levels of expertise, which are receiving, responding, valuing, organization and characterization.