Schema theory describes the process by which readers combine their own background knowledge with the information in a text to comprehend that text.
The term "schema" was first used in psychology with the meaning of "an active organization of past reactions or experiences”. It assumes that written text does not carry meaning by itself. Rather, a text only provides directions for readers as to how they should retrieve or construct meaning from their own previously acquired knowledge.
The theory of Schema can be used to help guide students to comprehend a text from the global point of view. Therefore, the roles of Schema theory in comprehension cannot be ignored.