Students' alternative conceptions of electricity

We have understandings of the physical world at the human scale which we have developed from infancy and which generally serve us well. But our understandings at the macro level (astrophysics) and the micro level (atomic physics) are modelled on understandings of human level phenomena.

These human level understandings let us down, for example, it can be useful to visualise electrons as golf balls in circular orbits but in fact they are better described as being probability clouds, similarly tunnelling behaviour of atomic particles and Heisenberg's Uncertainty Principle break one of the earliest rules we learnt as toddlers, Piaget's object permanence. Object permanence is the principle that an object placed in a container will continue to exist even if out of sight. In the world of atomic physics, objects can tunnel out of containers and there are limits to their observability, both of which break our fundamental human level understandings.

Electricity is a subatomic phenomenon which can be understood by analogy with water, it is convenient to use pressure for an analogue for voltage and flow rate as an analogue for current. This is a useful analogy but it does lead to misunderstandings.

"... mother lived the latter years of her life in the horrible suspicionthat electricity was dripping invisibly all over the house."
- James Thurber

http://standby.lbl.gov/pictures/AllOvertheHouse.gif

Caillot (1993) blames taking hydraulic analogies too far “Teaching strategies have also been pointed as an origin for the development of alternative conceptions. An example is the use of hydraulic analogies. “

The scientific view is that electric current is the circulation of electrons in a loop.

There are a number of common misconceptions about electricity which are incompatible with this view, many of which are related to taking the water analogy too far. Deakin University (2008) lists the following:

• In a circuit that contains wires, a battery and a globe, the battery stores electricity/power/current which flows to the globe where it is consumed.

• The thing that gets used up in an electric circuit is current.

• For a circuit that contains a battery and a globe, the globe lights up because:

o the current from each end of the battery clashes in the globe to provide the light (clashing- currents model)

o some of the current from one end of the battery is lost as it passes through the globe (consumption model)

o current from one end of the battery is all used up in the globe, making the second wire unnecessary (source-sink model).

• Batteries store a certain amount of electricity or charge.

Similar alternate conceptions which are compatible with a circulating current are noted in Hubber (2005):

• The Electric Power Companies supply electrons for your household current.

• “Electricity” is used up in electric circuits.

• Charge is used up in electric circuits.

• More devices in a series circuit means more current because devices “draw” current.

• Batteries store, and supply, electrons or “electricity” to the electric circuit.

• A wire from a battery to a bulb is all that is needed for the bulb to light up.

Most, if not all, of the alternative conceptions listed above can be categorised into

• the clashing-currents model,

• the consumption model and

• the source-sink model.

Ang (1993) confirms similar alternative conceptions, “battery is a store of electricity... one fifth of the pupils appear to hold the "clashing current" model of electric flow while about one-tenth of the sample appear to hold the "single wire" model of current flow.”

Crowley (2002) notes that in her research, a number of students, though in agreement with the scientific view, had reverted to their alternative conception by the exam.

References

Ang Kok Cheng, (1993) Primary Pupils' Conceptions About Some Aspects Of Electricity, AARE Conference 1993, retrieved 9/4/08, http://www.aare.edu.au/98pap/ang98205.htm

Caillot (1993), Learning Electricity and Electronics with Advanced Educational Technology, North Atlantic Treaty Organization Scientific Affairs, retrieved 9/4/08, http://books.google.com.au/books?id=0QuqBbRIWewC&pg=RA5-PA261&lpg=RA5-PA261&dq=alternate+conceptions+electricity&source=web&ots=BWmNoL4eJl&sig=Eb7c41LB-ISpATsVHFLG0t6I2FM&hl=en#PPP1,M1

Crowley, J.K. , (2002) Analogies Constructed by Students in a selective High School, Curtin University of Technology, retrieved 9/4/08, http://adt.curtin.edu.au/theses/available/adt-WCU20030923.135720/unrestricted/06chapter5.pdf

Deakin University (2008) School of Education Resources - Science and Environmental Education, retrieved 9/4/08 http://www.deakin.edu.au/arts-ed/education/sci-enviro-ed/early_years/electricity.php

Hubber (2005) POEs, Post Boxes, and IAIs, Science Teacher Association of Victoria, Physics Teachers’ Annual Conference, Monash University, Victoria February 8, 2005, retrieved 9/4/08 http://www.vicphysics.org/documents/events/stav2005/A2POESPH.doc

What I believe about how students learn

What I believe about how students learn

Students learn in many different ways. Gardiner's multiple intelligences gives some guidance, but only a little, the important thing is that they do learn in different ways and need to be given as many entry points or hooks as possible for learning.

Students construct mental models or understandings (1), the way students do that is highly individual. That means that students need to be given as many possible representations of the subject area as practical. We cannot predict the order or manner in which they will construct their understandings, that is why it is best if students are exposed to a rich set of learning materials and that they have some degree of autonomy in what order they engage with those materials.

For these reasons believe in self directed and project based learning. But I do abhor the occasional excesses of constructivism. There is a time for teaching content. Students cannot be expected to discover content just by being placed in an enriched environment, some stuff just has to be taught. Content is the building block for higher order thinking, unless students have a rich set of building blocks, they cannot do meaningful higher order thinking or problem solving.

The rate of discovery of human knowledge is increasing. Most of what is known has been discovered in our lifetimes. Our ability to access this knowledge base has increased with the Internet. It has been predicted that the sum of human knowledge will soon fit on a USB key (9). As a consequence, the teaching of content will become less important and the role of schools will be more about teaching students to be good problem solvers and learners (6).

Many of the problems that students will have to solve haven't been thought of yet. The skills that they most need are to be independent learners and to be able to solve ill-structured problems (7). Real world problems are ill-defined, they have poorly defined goal states, are multidisciplinary and have multiple or possibly no solutions. Schools should be equipping learners to solve real world problems. The real transfer issue for learning is, “does school learning transfer to real life?”, not “does project based learning X transfer to mathematics scores on standardised tests?”. This means that schools' horizons for self evaluation should extend far further than the end of year test results.

My vision for managing classes of students

I believe that education is best when it is authentic and relevant. Not all learning can be authentic and relevant, if it's the times tables, you just have to learn them, but when education can be authentic and relevant, it should be.

By relevant I mean important to self, by authentic I mean important to others. When you add the right tools and a collaborative environment you get the optimum situation for learning, a zone of proximal development, (4) or a state of flow (5).

Learning is best when it crosses subject boundaries, I believe the VELS (6) has got it right with its emphasis on multidisciplinary learning.

So my ideal classroom has students engaged in project based learning which crosses curriculum boundaries. Summative assessment is de-emphasised and collaborative learning is the norm (8). Students are working on projects which are relevant and authentic.

This may sound idealistic but I have run many classes which were like this (3) (8) (10) (11). Where students are disengaged from school, it is harder to involve students in project based learning. Greater levels of instruction and scaffolding are required but the goal remains the same, to move the students to a position where they are motivated to be independent and life long learners.

Tony Forster

17/5/08

Footnotes

(1) I believe that creating runnable mental models is an important component of higher order thinking http://tonyforster.blogspot.com/2008/02/problem-solving-creating-runnable.html

(2) Computer programming is one example of higher order thinking in a relevant and authentic context http://rupert.id.au/schoolgamemaker/why.htm

(3) The Games Programming Cluster of schools which I lead is an example of project based learning in a relevant and authentic context. The cluster of schools contains 3 teachers of the year, one of whom was awarded Microsoft's worlds best educational content in 2006.

http://learningevolves.wikispaces.com/Game+programming%2C+the+...

(4) Vygotsky's Zone of Proximal Development

http://en.wikipedia.org/wiki/Zone_of_proximal_development

(5) Mihály Csíkszentmihályi's theory of flow http://en.wikipedia.org/wiki/Flow_(psychology)

(6) The Victorian Essential Learning Standards http://vels.vcaa.vic.edu.au/index.html

(7) Jonassen holds that the solving of ill-defined problems should be one of the main goals of education Towards a design theory of problem solving

http://www.springerlink.com/content/tnk3716r532x0827/

(8) In Energy Efficiency and Demand Management, part of the Masters of Sustainable Energy which I lecture, I award 15% of course marks for contributions to Blackboard discussions. Collaborative work is encouraged, there is no penalty for receiving help on the discussion forum.

(9) I can't locate this assertion, it was quoted at the MCEETYA conference on educational games. I think it may have been Dianne Oblinger quoting Marc Prensky.

(10) http://rupert.id.au/schoolgamemaker/computerclub/index.html

(11) http://etrain.pbwiki.com/