Multimedia learning environments should be compatible with what we know about how people learn. A common error in the design of multimedia learning materials is to “clutter” the learning environment with extraneous information that increases the cognitive load for learners who are in the process of discovery what is important and what is decorative and distracting. The demands on working memory can exceed capacity when there is auditory input that does not match written text and there is visual animation and other movement to monitor at the same time, especially early in learning. The coherence principle calls for the removal of extraneous materials. The spatial contiguity principle refers to the need to keep printed text next to the visual display that it describes.