The learner's existing schema, which is defined here as an integrated structure of knowledge about a given topic, plays a critical role in new learning. Prior to or during learning, appropriate schemata should be activated in order to produce the best learning results. Instructional designers should systematically assess their target audience's pre-existing schemata and activate them in order to produce efficient and effective learning. Strategies available for this purpose include pre-treatment activities that engage learners in thinking about their existing schema prior to instruction and text enhancement to provide cues in learning material. Metaschemata, or students' knowledge about their own schemata, can be important; researchers have suggested that students learn how to evaluate their schemata and modify them as necessary. A list of 31 references is provided. (MES)