There is a theory of learning and teaching together and that is all. Results from many studies support this point of view as, also, does the evidence of commonsense. So, to be dogmatic (but with confidence) learning implies teaching and teaching implies learning. Sometimes the teacher and learner responsible for th joint process are obvious (a student at a desk and another person wearing an academic cap and gown). Sometimes, the teacher and learner are not so obviously distinct and turn out to be unexpected but, once-indicated, intuitively plausible entities.

p 33 as cited in: D. Psillos (2003) Science Education Research in the Knowledge-Based Society. p. 44. - Conversation, Cognition and Learning (1975)