would be one used for a history lesson on revolutions. This organizer "might be a statement that contrasts military uprisings with the physical and social changes involved in the Industrial Revolution" (Woolfolk et al., 2010, p. 289). Furthermore, one could also compare common aspects of other revolutions from different nations. 2. Expository Organizers "In contrast, expository organizers provide new knowledge that students will need to understand the upcoming information" (Woolfolk et al., 2010, p. 289). Expository organizers are often used when the new learning material is unfamiliar to the learner. They often relate what the learner already knows with the new and unfamiliar material—this in turn is aimed to make the unfamiliar material more plausible to the learner. An example which Ausubel and Floyd G. Robinson provide in their book School Learning: An Introduction To Educational Psychology is the concept of the Darwinian theory of evolution. To make the Darwinian theory of evolution more plausible, an expository organizer would have a combination of relatedness to general relevant knowledge that is already present, as well as relevance for the more detailed Darwinian theory. Essentially, expository organizers furnish an anchor in terms that are already familiar to the learner. Another example would be the concept of a right angle in a mathematics class. A teacher could ask students to point out examples of right angles that they can find in the classroom. By asking students to do this, it helps relates the students present knowledge of familiar classroom objects with the unfamiliar concept of a 90 degree right angle. Criticism "The most persuasively voiced criticism of advance organizers is that their definition and construction are vague and, therefore, that different researchers have varying concepts of what an organizer is and can only rely on intuition in constructing one-- since nowhere, claim the critics, is it specified what their criteria are and how they can be constructed" (Ausubel, 1978, p. 251). In a response to critics, Ausubel defends advance organizers by stating that there is no one specific example in constructing advance organizers as they "always depends on the nature of the learning material, the age of the learner, and his degree of prior familiarity with the learning passage" (Ausubel, 1978, p. 251). Another criticism of Ausubel’s advance organizers is that the critics often compare the idea of advance organizers with overviews. However, Ausubel has addressed that issue in saying that advance organizers