The modality effect refers to a cognitive load learning effect that occurs when a mixed-mode (partly visual and partly auditory) presentation of information is more effective than a single-mode (either visual or auditory alone) presentation of the same information. For learning to occur, novel material must be organised and incorporated into long-term memory via a limited working memory. For instruction to be effective, it has to be designed in ways in which the limitations of working memory are overcome. As distraction and interference impose an additional memory load, their impact on the limited working memory system has to be taken into consideration in a multimedia context where the different formats of words and pictures allow for many possible ways of presenting information. The instructional predictions that flow from the experimental work on the modality effect are straightforward. From a practical perspective, the modality effect provides guidelines for effective instruction.