A great dilemma lies at the heart of practical education. We wish to introduce students to the nature and practices of scientific enquiry, as it might be carried out by scientists. Learning by mimicking these processes, it is argued, will imbue our students with an understanding of scientific approaches, and thus they will learn the practices of science. Often such approaches can be given within a particular real-life context, which can be motivating. I know this argument well, and indeed have advocated this framework.1
However, problems emerge. Let’s consider two.
The first is that these approaches often conflate learning how to do a particular technique with applying that technique to a particular scenario. In other words, students are expected to learn how to do something, but at the same time know how to do it in an unfamiliar scenario. This should set off your cognitive load alarm bells. Now I know people may argue that students learned how to use the UV/vis spectrometer in the previous semester when doing the Beer-Lambert law, so they should be able to use it now for this kinetics experiment, but my experience is that students don’t transfer those skills well, and unless you’ve really focussed on teaching them the actual technique (as opposed to using the technique in a particular study), relying on previous experimental experience is not favourable.
Let’s park the cognitive load issue for a moment, and consider a deeper issue. In his wonderful essay, which should be compulsory reading for anyone setting foot in a teaching lab, Paul Kirschner discusses at length, the epistemology of practical education (epistemology meaning the way knowledge is acquired).2 He writes that we need to distinguish between teaching science and doing science. Drawing on the work of Woolnough and Allsop,3 and Anderson4 he describes the substantive structure of science – the body of knowledge making up science – and the syntactical structure of science – the habits and skills of those who practice science. Anderson’s short book is a wonderful read: he describes this distinction as “science” and “sciencing”. In teaching about the syntactical structure, or “sciencing”, Kirschner argues with some force that a mistake is made if we aim to use science practical work to reassert the substantive knowledge; we should instead be explicitly teaching the process of sciencing – how are these habits and skills are developed.
So: the previous two paragraphs have tried to summarise two issues that arise when one considers laboratory education that incorporate inquiry approaches; they often impose unrealistic demands on students requiring the learning about a technique and applying the technique to an unfamiliar scenario simultaneously; and their focus is on doing science as if it were a realistic scenario, rather than teaching how science is done.
An example in practice
How can such confusion manifest in practice? In our teaching labs, our Year 3 students used to complete several routine practicals, and then in their final few weeks complete an investigation. This approach has a lot going for it. Students get used to more advanced techniques in the first few expository experiments, and then being familiar with Advanced Things can launch into their investigation; an experiment they needed to scope out, design, and conduct. As their last formal laboratory exercise, this would be a good connection to their research project in Year 5.
In practice, it was a bloodbath. Students found it inordinately difficult to take on experimental design, and had little concept about the scope of the experiment, whether what they were doing was on the right path. I think it is instructive to relate these observed problems with the issues described above. We had not taught students how to use the techniques in the scenario they were going to be requiring them, and we had spent a long time telling them to verify known scientific facts, but not much about the actual processes involved in making these verifications.
Change was needed.
A few years ago at the Variety in Chemistry Education meeting in Edinburgh, Martin Pitt gave a 5-minute talk about a practice he had adopted: he gave students a chance to do a practical a second time. He found that even though everything else was the same, students in the second iteration were much more familiar with the equipment, had much greater understanding of the concept, and got much better quality data. This talk appealed to me very much at the time because (a) I was so impressed Martin was brave enough to attempt this (one can imagine the coffee room chat) and (b) it linked in very nicely with my emerging thought at the time about cognitive load.
So Martin is one piece of the jigsaw’s solution. A second is back to Kirchner’s essay. Must we Michael? Yes, we must. At the end, Kirschner presents some strategies for practice. This essay is a tour de force, but compared to the main body of the essay, these strategies seem a bit meek. However, there, just above the footnotes, he describes the divergent laboratory approach, a compromise between the typical recipes (highly structured) and the experimental approach (highly unstructured):
“The last approach can be regarded as a realistic compromise between the experimental and the academic laboratories and is called the divergent laboratory (Lerch, 1971). In the divergent lab, there should be parts of the experiment that are predetermined and standard for all students, but there should be many possible directions in which the experiment can develop after the initial stage. It provides the student with tasks similar to those encountered in an open ended or project (experimental) lab within a framework that is compatible with the various restrictions imposed as a result of the wider system of instructional organisation.”
Martin’s simple experiment had shown that by allowing students time and space to consider an experiment, they demonstrated greater understanding of the experiment and a better ability to gather experimental data. The divergent laboratory approach is one with a solid but pragmatic grounding in education literature. So here is the plan:
Students complete a recipe laboratory as usual. They learn the approaches, the types of data that are obtained, the quirks of the experiment. We call this Part 1: it is highly structured, and has the purpose of teaching students how to gather that data as well as get some baseline information for…
…for a subsequent exploration. Instead of finishing this experiment and moving on to another recipe, students continue with this experiment. But instead of following a recipe now, they move on to some other aspect. We call this Part 2 (naming isn’t our strong point). This investigative component allows them to explore some additional aspect of the system they have been studying, or use what they have been studying in the defined component to apply to some new scenario. The key thing is that the students have learned how to do what they are doing and the scope of that experiment, and then move to apply it to a new scenario. We repeat this three times throughout the students’ time with us so that the students become used to experimental design in a structured way. A problem with the old investigation model was that students eventually got some sense of what was needed, but never had the feedback loop to try it out again.
We call this approach unfinished recipes. We are giving students the start; the overall structure and scope, but the end depends on where they take it, how much they do, what variation they consider. There is still a lot of work to do (designing these experiments is hard). But lots of progress has been made. Students are designing experiments and approaches without direct recipes. They are learning sciencing. A colleague told me today that the turnaround has been remarkable – students are working in labs, are happy and know what they are doing.
YES THIS IS THE PHYSICAL CHEMISTRY LABORATORY NOW…
I’m very lucky to have the support of two fantastic demonstrators who were involved in the design of this approach and a lab technician who is patient to my last minute whims as well as colleagues involved in designing the unfinished recipes.
- McDonnell, C.; O’Connor, C.; Seery, M. K., Developing practical chemistry skills by means of student-driven problem based learning mini-projects. Chemistry Education Research and Practice 2007, 8 (2), 130-139.
- Kirschner, P. A., Epistemology, practical work and academic skills in science education. Science & Education 1992, 1 (3), 273-299.
- Woolnough, B. E.; Allsop, T., Practical work in science. Cambridge University Press: 1985.
- Anderson, R. O., The experience of science: A new perspective for laboratory teaching. Teachers College Press, Columbia University: New York, 1976.