Background Knowledge, or schema, refers to the experiences and/or prior understanding a reader brings to the text. It is important because each student approaches a text with varying levels of familiarity on any given topic. Background knowledge can be constructed directly or indirectly. For example, a direct experience is growing a plant from a seed. An indirect experience is reading books about growing plants.
Readers must not only demonstrate an ability to comprehend what they are currently reading, but integrate the new learning with prior knowledge. Furthermore, when new learning contradicts previous understandings, the reader must adjust their thinking to assimilate new information.