What do children's stories and HSC Physics have in common?

October 19, 2015

 

Question 23 (3 marks) 2005 HSC Physics

Explain how an understanding of black body radiation changed the direction of scientific thinking in the early twentieth century.

 

HSC Physics questions are among the most challenging of questions found across the range of HSC science courses.

 

I recently presented this item to my students for revision. I found to my dismay that most were bogging down in the detail.  They were writing laborious explanations of black body radiation and missing the point about how its study led to a fundamental change in physics form classical to quantum mechanics.

 

These students were flummoxed by the use of the verb ‘Explain’.

 

The students seemed to lack a metaview of the content. That is, whilst they could explain black body radiation and they could explain the photoelectric effect, they could not express the relationship between the two phenomena.

 

To successfully respond to this item, students need to describe the state of physics before describing the dilemma of black body radiation, and then explain how Physics changed.

A sample response:

 

Before the UV catastrophe of black body radiation was observed, the predominant view of light was in “classical” terms of being a wave.

In the late 19th century, the results from studies of black body radiation, where the intensity of light from a range of frequencies emitted from hot bodies, did not match results expected using a classical wave view of light.

Max Plank suggested that an atom can absorb or reemit energy only in discrete bundles (quanta). In this way he was able to resolve the dilemma of the UV catastrophe.

Five years later, Einstein would build on this quantum theory to explain the photoelectric effect, by introducing his photon theory. While Planck introduced the idea of quanta to fix problems in one specific experiment, Einstein went further to define it as a fundamental property of the electromagnetic field. [2]

 

Then it occurred to me that the structure of the response required was not that of description, explanation or argument – the genres commonly expected in science, but that of a narrative…

 

The Genre of Narrating

Narrative is used by cultures as a system for producing and reproducing social relations, for maintaining a sense of history, and for securing particular ways of seeing and knowing… In Australia, for example, the stories of the Aboriginal cultures are vastly different from mainstream Western Culture.[1]

 

Narratives can be thought of as being concerned the temporal and/or causal structuring of events. Simple stories also include complications that are generally resolved by the end of the story.

 

We are all familiar with the story of Little Red Riding Hood. It follows the familiar simple narrative structure: Orientation – complication – resolution.

 

 

Narrative structures in Physics

Narrative structures are used in the NSW HSC Physics course are concerned with the temporal and/or causal sequencing of a series of events. Typically the HSC Physics demands more than just a mere retelling of events. The narrative arc of physics changes direction with added complications of unexpected results that must be resolved.

 

The purpose of narratives in Physics is often to demonstrate the consequences of experimental data that does not fit an existing predominant theory. However, the narrative purpose may differ. For instance, to demonstrate how changes in technology have changed scientific theory, or how applications of science have changed society or the environment.

 

Question 23 (3 marks) 2005 HSC Physics

Explain how an understanding of black body radiation changed the direction of scientific thinking in the early twentieth century.

 

The scaffolded response below demonstrates clearly its narrative structure.

The structure of this response is a little more sophisticated than the example provided of ‘Little Red Riding Hood’, in that it concludes with a coda or evaluation.

 

When presented this way, it is clear why students are flummoxed by the question.  The verb ‘explain’ is not used is not used to elicit a simple cause and effect response as in these two items from HSC Physics:

 

Question 26 (a) 2007 HSC Physics

Explain why AC is preferable to DC as an input current for transformers. (2)

 

Or

 

Question 23 (c) 2006 HSC Physics

Explain how the addition of trace amounts of certain elements, such as phosphorus, can change the electrical resistance of semiconductors at a given temperature.

 

Consider the following question from the 2009 HSC Physics paper. The response required follows the narrative structure.

 

Question 31 (e) (6 marks) 2009 HSC Physics

 

Theories and experiments not only help increase our understanding but also generate new questions. Use the standard model of matter to support this statement.

 

Question 31 (a) (6 Marks) 2009 HSC Physics

Marsden and Geiger conducted an experiment in which they fired alpha particles at a thin gold foil. Most of the particles passed straight through.

Describe how Rutherford’s model of the atom explained these results. (2)

Describe TWO problems associated with Rutherford’s model and how these were explained by Bohr’s model of the hydrogen atom. (4)

 

This question has been scaffolded for the students. The orientation has been separated as a separate part question. My data-free opinion is that students would find this question easier to respond to than the previous unscaffolded questions.

 

 

Question 24 (6 marks) 2008 HSC Physics

How did Einstein’s theory of special relativity and his explanation of the photoelectric effect lead to the reconceptualisation of the model of light?

 

Question 24 above is another example of an item that is requiring a narrative response. Board of Studies notes from the marking centre clearly state that many students, whilst could explain the phenomena but could not relate them. 

 

In the better responses, candidates showed evidence of planning and included two

reconceptualisations of light and related them to the two named areas investigated by Einstein. Better responses stated both the models of light before and after the reconceptualisations.

Weaker responses discussed the two areas investigated by Einstein (the photoelectric effect and special relativity) but could not clearly relate them to the reconceptualisations of light. They had difficulties understanding the idea of a reconceptualisation. In the weaker responses, candidates often stated that light was constant rather than the speed of light being constant. Some weaker responses showed a lack of planning and the information did not always follow a coherent pattern. [5]

 

 

 

Conclusion

What do Children's stories and HSC Physics have in common?

 

It is clear that the HSC Physics papers regularly include items that require students to sequence historical events in time and through causation. An understanding of a simple narrative structure provides students with a scaffold or metaview to respond successfully to these items.

 

References

[1] Peter Knapp, 1992, Met West Literacy & Learning Program Resource Book. North Parramatta, Metropolitan West Literacy and Learning Program, NSW DET.

[2] Andrew Zimmerman Jones;  Blackbody Radiation - The Ultraviolet Catastrophe About.com Guide http://physics.about.com/od/quantumphysics/a/blackbody_2.htm

[3] http://en.wikipedia.org/wiki/File:Little_Red_Riding_Hood_-_Project_Gutenberg_etext_1993.jpg

[4] STANSW, Excel Success One HSC Physics, 2010, Glebe, Pascal Press

[5] 2008 HSC Notes from the Marking Centre Physics http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2008exams/pdf_doc/physics-notes-08.pdf

 

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