"Aiming-high and missing: A more practical pedagogical problem – but one which I would regard as highly significant – is that it is very hard for students to learn difficult concepts unless these concepts are presented as unambiguously as possible.
Ambiguity interferes with learning, since each additional possibility multiplies uncertainty in a geometric fashion. I am not sure whether this is numerically exact, but it seems as if adding the first uncertainty to an explanation doubles the cognitive load – because there are now two parallel and diverging possibilities; both of which must now be known, understood and compared. Adding a second uncertainty to the first therefore quadruples the cognitive load, a third uncertainty will render comprehension and memorizing 16-fold more difficult – and so on.
This analysis implies that the primary mode of most science teaching must be dogmatic; that is to say, a science teacher must initially make a choice about the single most correct interpretation of evidence and the single most correct conclusion – and must restrict the initial presentation to this clear and simple exposition.
Only after the teacher is confident that most students have understood this clear and simple account (and preferably after leaving this unified exposition to be assimilated overnight) should the teacher add layers of uncertainly, debate, distension and complication to the simple account. Premature challenging of main-stream science, debates over competing hypotheses, and uncertainties engendered by free-form discussions are likely to interfere with learning.
Therefore, for many students studying science, it is better to leave them with a clear grasp of the single best version of a concept, than permanently to confuse them with further accounts; or potentially to drive-out or corrupt a clear and approximately-accurate memorization by interference from related – similar but not quite equivalent – explanations, qualifications and nuances.
Obviously, this does not mean the science classroom should be a wholly one-way street of discourse streaming from the teacher into the taught – of relentless pontification from one side and silent absorption on the other side. On the contrary, student feed- back (via perceived visual signals and some spoken enquiries or comments) is necessary for the teacher to monitor the learning process. (This is one reason why real time, real life lectures retain their value; and why to be successful lectures need small-enough and well-designed lecture rooms such that the lecturer and his audience remain in sensory contact.)
Science teaching could and should be made more interesting for students than it usually is – but it should be made more interesting while still being science; and not at the cost of stopping studying science and instead engaging in mere science-themed chit-chat. In reality, the flow of scientific knowledge is likely to be unidirectional.
If teachers aim too-high for students whose motivation, intelligence and preparation are insufficient; or if teachers try to make students run before they can even crawl – especially for students who lack the background and ability ever to do anything more than walk; or if teachers overwrite their clearest and simplest message by smothering it in confused discussions and pseudo-scientific de- bates – then teachers risk failing to enable the attainment of even basic scientific knowledge and competence in their students.
Instead, for the early years of science teaching, the basic assumption ought to be that the student is there to learn science; not to confront science. The basic attitude being taught should be one of humility before the science being studied."
Knowledge first, critique later: why it is a mistake for science education to encourage junior students to discuss, challenge and debate scientific knowledge. Med Hypotheses. 2010 74(2): 211-213
Bruce G. Charlton
Editor-in-Chief – Medical Hypotheses
Professor of Theoretical Medicine
University of Buckingham, UK.