Nature of Science for Teaching

David Geelan

What is science?

There are at least four parts to a definition:• A set of methods and standards for creating

and testing knowledge claims• A body of knowledge that has been created

by scientists and has (so far) succeeded in passing such testing

• The domain of human knowledge that deals with the natural world

• A world view or set of values – a commitment to the methods and standards of science in their appropriate domain

Teaching Science

• When we teach science we are involved in developing in students the knowledge, skills and attitudes that allow them to engage with science

• Teaching science is much more than transmitting content knowledge

Induction and Deduction

• In logic, ‘induction’ describes the building up of broad, general laws or theories from looking at individual cases and examples

• ‘Deduction’ describes the reverse process of predicting individual cases from the broad general rules

Inductivism

• The theory of natural science that began with Francis Bacon

• Inductivism is the belief that scientific theories arise through repeated observations of the natural world

• Sufficient careful observations of the same phenomenon allow scientists to propose a general rule

Example of Inductivism

• A simple example of inductive reasoning is the statement ‘All swans are white’ – sufficient experiences of seeing white swans in Europe might allow this to be stated as a general rule – but when you get to Australia and see black swans, the rule is no longer considered valid

Critiques of Inductivism• There is a logical problem with

inductivism: where does the ‘principle of induction’ (the idea that sufficient observations allow us to state a law’) come from? It’s not out there in the natural world, so the only way we could find it is… by induction!

• This is circular reasoning

Critiques of Inductivism

• A number of philosophers of science, including Popper and Kuhn, have described alternative ways of thinking about science to inductivism

Scientific Methods• We shouldn’t teach our students about ‘the

scientific method’ – science is not that simple – but about ‘scientific methods’

• Most scientific methods arise out of inductivism, or its logical equivalent, ‘verificationism’

• That is, scientists propose an hypothesis and then seek evidence to verify it

Scientific Methods• (read the relevant literature to know what has been

done before)• Propose an hypothesis• Determine what kind of evidence would verify

(support) or falsify the hypothesis• Gather the evidence (dependent, independent and

controlled variables)• Analyse it to test whether it supports the hypothesis• Critically evaluate your methods and actions

Scientists and Students

• What high school students are doing is both similar and different to what scientists are doing:

Similarities:

• Both testing knowledge claims (ideally through experiment)

• Both using scientific methods

Scientists and Students

Differences

• Scientists are creating new knowledge

• Students are creating – for themselves, in their own minds – new understandings of existing knowledge

Sources of Evidence for Knowledge Claims

• Authority

• Experiment

• Experience (informal experiment)

Science Education

• Unless we allow students to gather evidence in the laboratory with which to test knowledge claims, their only source of evidence is our authority

• That would be what’s called ‘indoctrination’

Conceptual Change Theory

David Geelan

Conceptual Change• In most cases, particularly in high

school, students come to the science classroom with an existing ‘theory’ about a phenomenon

• This theory might come from their earlier science education, but is more likely to come from their experience of the world

Conceptual Change• This means that teaching a new science

concept is not simply a matter of transferring the science into an empty vessel

• What is most often occurring in science education (if it’s successful) is a conceptual change from one concept to another

Misconceptions/whatever

• In science education, students’ existing beliefs and theories have been described as: misconceptions, preconceptions, children’s science, alternative conceptions, naïve conceptions…

Conceptual Change• This change is unlikely to occur based only

on our authority – students need evidence from the physical world

• That evidence is obtained in the lab or demo• But for the evidence to actually mean

anything, the student needs to know in very clear terms what a particular result implies

Conceptual Change

• To do that, the new concept that we are offering – the scientific concept – has to be seen as:– intelligible– plausible– fruitful

(Posner, Strike, Hewson & Gertzog)

Predict, Observe, Explain

• One strategy for allowing students to compare their existing concepts to the scientific ones is a ‘predict, observe, explain’ activity

• Students are asked to predict the result of an experiment. They will do this based on their existing knowledge

Predict, Observe, Explain• They then observe the experiment, and

see whether their prediction was supported or falsified, and are asked to explain their observation

• With a well designed experiment, the scientific concept will explain the results better (more fully and clearly) than the naïve conception that the students hold

Evidence

• There are a variety of other strategies that teachers can use to allow students to gather evidence with which to test both their existing ways of understanding the world and the scientific ways that are being offered to them

Conclusion

• The important point is that any science education program worthy of the name gives students scientific, empirical evidence, not just appeal to authority

• We recommend that 20-25% of all science classes have a lab or demonstration component