Content that is presented prior to learning and that can be used by students to organize and clarify new incoming information. The purpose is to build a bridge from prior knowledge to the new information that encourages the understanding, learning, and retention of the new concept.
By activating relevant prior knowledge, advance organizers also help students stay focused on the subject. An advance organizer can come in a variety of forms. It could be a brief, abstract prose passage based on the student’s existing knowledge, which serves as a transitional statement for new learning or a diagram that directs the student toward the main ideas and relationships in the new content.
For further explanation:
The CTER Program provides WikEd, which contains an informative entry on advance organizers that includes information about the history, applications, and types of advance organizers.