Prior learning as an epistemological block

Prior learning as an epistemological block?: The octet rule – an example from science education

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Abstract

Two decades of research in science education have examined young peoples’ ideas prior to formal teaching, and have considered how such preconceptions might act as a block to effective learning of orthodox science. Considerable efforts have been expended in developing activities to challenge ‘misconceptions’ that are found to be common in such naive thinking, to prepare the way for the desired conceptual changes.

If the learner’s lay ideas can act as a block to effective curricular learning, then how much more efficacious could ideas acquired in formal instruction, presented with the authority of the teacher and of science. Science educators accept that the acquisition of complex scientific concepts is not an all-or-nothing event: often there is the need for learners to revisit concepts over a number of years, increasing the sophistication of the exposition, and the range of contexts in which the idea is applied. The concept as met at age 7 will not be presented as fully as when revisited at age 17.

For educators science is a way of knowing the world in terms of models and theories that are judged according to logical, empirical and utility criteria – successful scientific theories comprise self-consistent frameworks of ideas that are not falsified by experiment and which have explanatory value in discussing a range of phenomena. Research shows that science learners do not have the same epistemologies of science: they see science as factual rather than conjectural, as absolute rather than relative, and they may accept as ‘explanation’ that which is merely definition or tautology, that which is anthropomorphic and/or teleology, that which is merely correlational, and that which is merely description. Consequently care should be taking when introducing elementary ideas that any simplifications and generalisations that are used are not presented in such a way that they might later act as blocks to progression in the development of the concept area.

This argument is illustrated by consideration of what is often known in chemistry as the ‘octet rule’. This (used correctly) is a heuristic for determining which chemical species (atoms, molecules, ions etc.) are likely to be relatively stable. Evidence will be presented to demonstrate that for many students this ‘rule of thumb’ learnt in introductory science courses, takes on the status of a causal framework that is used to ‘explain’ chemical changes. Atoms and the like are so novel to youngsters that ideas about this world presented with the authority of science seem to become deeply established (there are few preconceptions to interfere.) The idea that atoms need to obtain ‘full outer shells’ is not only widely applied by students where it is inconsistent on its own terms, but it can act as a block to learning the more difficult ideas about chemical changes met later in science.

Content:

Prelude:
Introduction: meaningful learning and learning blocks?
A possible typology of learning blocks
Null learning blocks
Substantive learning blocks
Ontological learning blocks?
Epistemological learning blocks?
The octet rule
Limitations of the octet rule
The octet explanatory principle?
Examples of the use of the octet explanatory principle:
Misunderstanding the ionic bond
Misunderstanding ionisation energy
Conclusions regarding student use of the octet rule.
Presentation of the octet rule
Confusion between octets, full shells and noble gas electronic configurations
The octet rule expressed as an explanatory principle, rather than a heuristic device
Chemical processes explained in anthropomorphic terms
Implication that common materials are formed from atomised matter
The status of scientific knowledge
The role of explanation in student discourse, science teaching and science
Suggestions for changing the teaching of chemistry

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