David Ausubel developed the theory of meaningful learning which emphasizes relating new information to existing knowledge through subsumption. He proposed two types of advance organizers - exposition and comparison types - to present overviews before detailed lessons. Meaningful learning occurs through four processes: derivative subsumption relating examples to concepts, correlative subsumption extending concepts, superordinate learning identifying concepts, and combinatorial learning relating ideas analogously. Teachers should present general ideas first then examples, integrate new and old information, and use advance organizers and multiple examples.