Practical work: theory or practice?

Literature on laboratory education over the last four decades (and more, I’m sure) has a lot to say on the role of practical work in undergraduate curricula. Indeed Baird Lloyd (1992) surveys opinions on the role of practical work in North American General Chemistry syllabi over the course of the 20th century and opens with this delicious quote, apparently offered by a student in 1928 in a $10 competition:

Chemistry laboratory is so intimately connected with the science of chemistry, that, without experimentation, the true spirit of the science cannot possibly be acquired. 

I love this quote because it captures so nicely the sense that laboratory work is at the heart of chemistry teaching – its implicit role in the teaching of chemistry is unquestionable. And although it has been questioned a lot, repeatedly, over the following decades; not many today would advocate a chemistry syllabus that did not contain laboratory work.

I feel another aspect of our consideration of chemistry labs is often unchallenged, and needs to be. That is the notion that chemistry laboratories are in some way proving ground for what students come across in lectures. That they provide an opportunity for students to visualise and see for themselves what the teacher or lecturer was talking about. Or more laudably, to even “discover” for themselves by following a controlled experiment a particular relationship. Didn’t believe it in class that an acid and an alcohol make an ester? Well now you are in labs, you can prove it. Can’t imagine that vapour pressure increases with temperature? Then come on in – we have just the practical for you. Faraday said that he was never able to make a fact his own without seeing it. But then again, he was a great demonstrator.

A problem with this on an operational level, especially at university, and especially in the physical chemistry laboratory, is that is near impossible to schedule practicals so that they follow on from the introduction of theory in class. This leads to the annual complaint from students that they can’t do the practical because they haven’t done the theory. Your students are saying this, if you haven’t heard them, you need to tune your surveys.

It’s an entirely understandable sentiment from students because we situate practicals as a subsidiary of lectures. But this is a false relationship for a variety of reasons. The first is that if you accept a model whereby you teach students chemistry content in lectures, why is there a need to supplement this teaching with a re-teaching of a sub-set of topics, arbitrarily chosen based on the whim of a lab course organiser and the size of a department’s budget? Secondly, although we aim to re-teach, or hit home some major principle again in lab work, we don’t really assess that. We might grade students’ lab report and give feedback, but it is not relevant to them as they won’t need to know it again in that context. The lab report is done. And finally, the model completely undermines the true role of practical work and value it can offer the curriculum.

A different model

When we design lecture courses, we don’t really give much thought to the labs that will go with them. Lecture course content has evolved rapidly to keep up to date with new chemistry; lab development is much slower. So why not the other way around? Why not design lab courses independent of lectures? Lecture courses are one area of the curriculum to learn – typically the content of the curriculum; laboratory courses are another. And what might the role here be?

Woolnough and Allsop (1985), who make a clear and convincing argument for cutting the “Gordian knot” between theory and practice, instead advocate a syllabus that has three aims:

  1. developing practical skills and techniques.
  2. being a problem-solving chemist.
  3. getting a “feel for phenomena”.

The detail of how this can be done is the subject of their book, but involves a syllabus that has “exercises, investigations, and experiences”. To me these amount to the “process” of chemistry. On a general level, I think this approach is worth consideration as it has several impacts on teaching and learning in practice.

Impacts on teaching and learning

Cutting the link between theory and practice means that there is no longer a need to examine students’ understanding of chemistry concepts by proxy. Long introductions, much hated by students, which aim to get the student to understand the theory behind the topic at hand by rephrasing what is given to them in a lab manual, are obsolete. A properly designed syllabus removes the need for students to have had lectures in a particular topic before a lab course. Pre-lab questions can move away from being about random bits of theory and focus on the relationships in the experiment. There is no need for pointless post-lab questions that try to squeeze in a bit more theory.

Instead, students will need to approach the lab with some kind of model for what is happening. This does not need to be the actual equations they learn in lectures. Some thought means they may be able to draw on prior knowledge to inform that model. Of course, the practical will likely involve using some aspect of what they cover or will cover in lectures, but at the stage of doing the practical, it is the fundamental relationship they are considering and exploring. Approaching the lab with a model of a relationship (clearly I am in phys chem labs here!) and exploring that relationship is better reflecting the nature of science, and focussing students attention on the study in question. Group discussions and sharing data are more meaningful. Perhaps labs could even inform future lectures rather than rely on past ones! A final advantage is the reassertion of practical skills and techniques as a valuable aspect of laboratory work.

A key point here is that the laboratory content is appropriate for the level of the curriculum, just as it is when we design lectures. This approach is not advocating random discovery – quite the opposite. But free of the bond with associated lectures, there is scope to develop a much more coherent, independent, and more genuinely complementary laboratory course.

References

Baird W. Lloyd, The 20th Century General Chemistry Laboratory: its various faces, J. Chem. Ed., 1992, 69(11), 866-869.

Brian Woolnaugh and Terry Allsop (1985) Practical Work in Science, Cambridge University Press.

1928 quote

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