Towards a philosophy of measurement in the science teaching laboratory

If the university is to do justice to its mission of producing science graduates of the highest quality, it needs to embed a philosophy of science that places the role of observation at the forefront of its curricula.

This was the thrust of Professor Andy Buffler's inaugural lecture on 10 September, titled Science and observation: measuring for knowledge.

Head of UCT's Department of Physics, Buffler spends much of his research time in the realm of applied nuclear physics. Take his work on positron emission particle tracking (PEPT) as an example '“ an effective method of studying the flow of material using radioactive tracers and a medical PET scanner. In partnership with Dr Indresan Govender (also from UCT's Department of Physics), Buffler established the second operational PEPT laboratory in the world a short drive east of UCT, at iThemba LABS.

But the physicist also takes great care in passing on his expertise to students '“ a passion demonstrated in his early UCT career, which began with the Centre for Higher Education Development, and recognised in 2002 with a Distinguished Teacher Award.

Education by experimentation

Twenty years since the dawn of democracy, the South African education system remains a challenge. Of particular concern is the state of mathematics and physical science teaching, says Buffler '“ there is evidence that teachers' abilities to deliver the curriculum is waning across the sector.

"Laboratory work and the teaching of experimentation in science in particular has suffered. Equipment is safely locked away in fear of theft or breakage, and teachers' confidence to lead laboratory work is reduced within the context of ever-changing curricula."

As part of a large research programme focussed on lab teaching in physics, incoming science students were surveyed on their experiences of lab work at school.

"We have consistently found that only around half report that they undertook hands-on science activities themselves at their school," says Buffler. "One quarter report that only the teacher used the apparatus (in demonstration mode) and one quarter report that they had no experience with experimental work at all. And these are UCT students!"

Does science uncover truth?

One of the main consequences of poor laboratory work at school is a cementing of a view in the minds of school learners and university students that nature is predictable and deterministic, "and unexpected results should be regarded as wrong, a consequence of faulty apparatus or student error", says Buffler.

The majority of students believe that measurement within the scientific context is an exact activity, and will yield a "point-like" result, he says '“ meaning that, in principle, it is possible to reduce measurement uncertainty to zero.

This is not an entirely local problem, notes Buffler. Students in Australia, England, France, Germany, Greece and the United States demonstrated similar faith in this epistemology, "even though they are able to apply rigorous techniques of data analysis and uncertainty estimates", he says. "However at UCT we need to constantly recognise and respond to the additional challenges associated with the diversity in the educational experiences of our students, particularly in mathematics and science. A communication of a consistent philosophy of science in our laboratory curricula will produce tangible advantages.

"Personally I would advocate a philosophical framework in which the scientific model is seen to mediate between high-level theory and the results from observation in the real world."

Embrace uncertainty

There's a strong link between young people's views of the nature of science and their ability to develop the tools of science, says Buffler.

"For example, in the most naïve sense, a belief in science as an activity to uncover the truths of nature results in approaches to learning science which are aligned with memorising facts and picking formulae to solve numerical problems."

The role of measurement uncertainty '“ an aspect of laboratory work often maligned by students and instructors alike '“ should be developed as a natural aspect of measurement, argues Buffler: "We have shown that the so-called ISO-GUM [Guide to the Expression of Uncertainty in Measurement] approach, as recommended by the International Organisation for Standardisation, offers tremendous pedagogical advantage, since measurement uncertainty is associated with the quality of the knowledge gained as a consequence of the measurement."

Teachers should present students with laboratory tasks for which the outcome was unknown, cast in authentic contexts and aligned in with real science, says Buffler. This not only adds motivation to the experiment, but could be linked to a useful philosophical framework of science.

"Parents with young kids, take note: do experiments with your kids that lead to unexpected results, and then don't look too confused yourself."

Measurement for advancement

Buffler's applied research rests heavily on measurement. All measurement, says Buffler, is governed by a set of international standards. For instance, our understanding of weight can be traced to the international prototype kilogram that sits at the International Bureau of Weights and Measures in Paris. Think of our neutron beam in the same way as the standard kilogram.

"In recent times we have developed our fast neutron beams at iThemba LABS to a level which allows us to be part of some interesting projects, such as calibrating the same radiation detector that is presently on the Curiosity on Mars, or others which are presently flying on the International Space Station. A particular interest of mine is the consideration of new techniques for the detection of explosives in luggage, for example. Without careful measurement of the radiation we use to interrogate the object, none of these applications would be possible.

Speaking of the significance of this kind of applied research for UCT and South Africa, Buffler explains: "'Big science' is related to 'big development'. The positioning of UCT as the premier university on the African continent, with growing international reputation, places us at the gateway into Africa. Physics drives technological development, which in turn drives social development. Applied physics research at UCT locates itself within this institutional goal."

A history of scientific endeavour

While arguing for a philosophy of measurement, Buffler's lecture also traced a history of scientific endeavour '“ from Plato and Aristotle through to Galileo, Newton and UCT's own RW James, a physicist who was also a member of Sir Ernest Shackleton's ill-fated expedition to Antarctica aboard the Endurance:

"In the foyer of the RW James building at UCT is a cabinet with a few memorabilia associated with RW James. Included in the collection is an X-ray spectrometer on which both of UCT's science-related Nobel Prize winners, Aaron Klug and Allan Cormack, learnt their art of scientific measurement. In the audience this evening lies the potential to follow these great scientists."

Listen to the audio recording of Prof Buffler's lecture

Read Prof Buffler's inaugural paper