This Digest provides educators with an overview of some important facets of cognitive science research and suggests implications for classroom assessment. Education researchers study the thinking of experts in various subject areas to understand the concepts and procedures that are the most important to teach and to help determine how to move students along the continuum towards real-world subject mastery. Researchers consider the common pathways toward acquiring knowledge in the classroom. More research has been done about domain structure in some disciplines than in others, but much work is being done on how learners store and access knowledge. Assessment designers can use findings from cognitive science. Cognitive science calls for test developers to work from a deep knowledge of the central concepts and principles of a given subject area and to identify tasks that let students demonstrate their understanding and skills, as opposed to rote memorization. Overall, cognitive science asks test developers to let students show what they know and can do. At the classroom assessment level, cognitive science findings encourage teachers to teach learners how and when to apply approaches and procedures and to teach metacognitive skills and problem solving. Teachers need to be aware that acquiring important knowledge and skills at an in-depth level takes a significant amount of time, practice, and feedback. (Contains 20 references.) (SLD)