Mantle plume theory has been widely, but not universally, accepted in the geo-sciences for several decades, but recent critical evaluation has led to an intense debate regarding the existence of mantle plumes. I provide an overview of mantle plume theory and the current skepticism. The results of a poll taken after the 2005 American Geophysical Union Chapman Conference, The Great Plume Debate, are presented to give general readers a sense of which arguments specialists consider strongest in favor of, or opposing, mantle plume theory. Mantle plume theory first appeared in introductory textbooks in the late 1970s, and the theory was presented in most introductory textbooks by the end of the 1980s. In light of the current debate, most recent editions have introduced language indicting debate and uncertainty about mantle plume theory. However, none of these textbooks offers any alternative hypotheses; advanced textbooks also give little attention to alternative hypotheses. I assert that, without the presentation of alternative theories, students will simply accept the one presented as fact. The current debate should be seen as a teaching opportunity. It should be conveyed to students that this debate reflects the fact that geology is a very dynamic science and that first-order problems in the geosciences remain to be addressed by current and future generations.