In part 1, I offered a number of justifications for the near universal practice in the UK of teaching science through the use of investigations and experiments. In this section, I will focus on the first justification which related to the fact that this was the best way for students to learn science content, e.g. that iron rusts when in contact with both water and air.

I want to start with a little biographical note. Educationally, I came of age in a particular tradition, one which inculcated in me a very strong belief that the best way for an individual to learn something was by discovering it for themselves. I tried to plan my lessons around suitable activities like research, investigations and peer-to-peer discussion (see Driver, 1999, Introduction).

That way of thinking started to crumble when I read the Sutton Trust’s “What Makes Great Teaching?” report. Steered by Professor Robert Coe (who is fantastic – see also here), this report looks at a number of aspects of great teaching. The report acknowledges that it is difficult to actually identify what does work in terms of teaching, but we can certainly identify what does not work. Some of these things made a lot of sense to me as ineffective; don’t put students in groups by ability? Sure no problem. Don’t use praise lavishly? Yup I can buy that. Don’t teach to students preferred learning style? Pah – everyone knows that.

But imagine my surprise when I read that “Enthusiasm for ‘discovery learning’ is not supported by research evidence, which broadly favours direct instruction (Kirschner et al, 2006). Although learners do need to build new understanding on what they already know, if teachers want them to learn new ideas, knowledge or methods they need to teach them directly.”

This, rather ironically, set me on my own journey of discovery. Through reading scholarly blogs by people such as Daniel Willingham, Andrew Old, Tom Bennett, David Didau and Greg Ashman as well as the Kirschner (2006) article itself, I became a convert to a different educational tradition, one that prized effective instruction to secure a deep and lasting knowledge.

So I found myself an acolyte of a new religion. One of the foundational attitudes of this religion was an appreciation of basic cognitive science. The most axiomatic principle here is that thinking is hard. Really hard. This is because the bit of our brain which does the thinking – our working memory – is almost laughably limited. It can only ever hold a few items and even then not for long. It’s why we can’t remember long strings of numbers. It’s why we need a pen and paper to do long multiplication. It’s why when I go to the kitchen to fetch something but take my phone out to check twitter, I instantaneously forget why I was going to the kitchen.

However, if we know more stuff, then thinking becomes easier. So I can learn new scientific concepts and apply them far more quickly than my students. Not because I am more intelligent than they are, but because I’ve learnt so much science before that my brain has constructed a schema – a body of knowledge which allows my working memory to function more effectively. Willingham has a number of further examples here where he proves the point better than I ever could: having more knowledge helps you think, memorise and learn.

The reason why Kirschner (2006) argued that “discovery learning” doesn’t work is because by definition students are being asked to learn about something for which they do not have that background body of knowledge. This leads to a cognitive overload – a state where the student cannot think well enough to be able to accurately or efficiently assimilate new knowledge.

That’s why we need teachers – they chop up the knowledge into digestible parts. They encourage and promote methods by which knowledge is gradually structured and built up over time. (As a teacher, it of course behoves me to point out that if all this is news to you, please please read some of the links here – without this knowledge of how cognition works it will be that much harder for me to convey my point properly. Meta.)

In a really fascinating and wide-ranging piece, Paul Kirschner (of 2006 fame) applies this logic to the field of teaching science through experiments. If students are being asked to design their own practicals, identify all the variables, carry out a detailed method, make and record observations in a properly constructed table, plot results on a graph, make a relevant conclusion about the scientific principle under investigation and reflect and evaluate their method, they are surely doomed from the start. It is simply too many things to hold in the mind at once. Even the basic process of taking readings from a ruler whilst thinking about the scientific purpose of those readings is enough to overload cognitive capacity. Students will end up doing only one thing – either measuring or thinking, but not both.

Kirschner makes another central point about the differences between novices and experts. Scientific experts do indeed generally work through discovery models. They plan their own investigations and devise their own theories and hypotheses. But my students are not experts. They do not have years of accumulated scientific knowledge and experience. Because of this, they are not physiologically equipped to operate at the same level.

Just think about the length of time it took before humanity discovered some of the most basic tenets of modern science. It took until the 18th Century before Antoine Lavoisier discovered the law of Conservation of Mass. That’s tens of thousands of years of humanity before anyone worked out that when you burn toast, its mass isn’t destroyed. Classical mechanics, optics, planetary rotation, thermodynamics – it took humanities’ greatest minds working in concert to discover and formulate these laws. Minds that were naturally gifted but also strengthened and developed through years of practice, knowledge and experience. I might have high expectations of my students, but I don’t think I’m being unreasonable if I doubt their ability to match these achievements.

So do I think that students designing their own experiment is the best way for them to learn that water and air are required for a nail to rust? I do not. Do I think that students planning their own investigations into springs is the best way for them to learn Hooke’s law? I do not. And I think that the scholarly evidence supports this conclusion.

But do I think that I have proved that science practicals are a waste of time? With this too, I do not. I suppose you will just have to read part three as well.

Introduction: are we wasting our time? – part 1

The Cognitive Science of Practical Science – part 2

Thinking Scientifically – part 3

Do Science Practicals Boost Engagement? – part 4

Mary the Super Scientists – part 5

Teaching Practical Skills: If You Aren’t A Science Teacher, Leave Me Alone – part 6

Conclusion – part 7

Addendum – Abrahams and Millar

Through Twitter I was pointed to this research paper by Ian Abrahams and Robin Millar. When I looked at it I realised that I had actually read it during my PGCE year as the diagram of the realm or ideas + the realm of observables was one that I had used before. In short, the researchers visited 25 lessons to see whether or not the practical work led to any increases in the students’ ability to learn specific science content (as opposed to skills). They conclude that these lessons only promoted student ability to follow the instructions rather than learn the specific content. Unfortunately the paper is limited by a relatively small sample size of 25 lessons, the fact that preliminary and subsequent lessons were not observed, and that there was no opportunity in the study to come back six months later and look at long-term retention. I am also generally sceptical of conclusions drawn from lesson observations.

The authors’ basic idea that student understanding of the link between the realm of ideas and the realm of observables is incredibly difficult to promote is not dissimilar to my presentation above. I think the work of Kirschner et. al. suggests a conceptual framework as to why it is so difficult – it is simply too burdensome on the working memory. I am not sure I agree with one of their suggestions which is that the teacher promotes the domain of ideas simultaneously with the students working on the domain of observables. As per Kirschner, I think this is too taxing for student working memory. Generally, Kirschner’s strong theoretical model (absent from the A&M paper), based on weighty evidence, is what compels me.

There is a prettier version of the paper here

SCORE and ASE review of the research

This review of the research contains many similar ideas to the Abrahams and Millar paper. I personally found the lack of any quantitative research in the review to be frustrating. There were only two sources (to my knowledge) that actually attempted to put a number to the learning impact of science practicals. The author concedes that there are a lot of surveys and questionnaires used as sources of evidence.

There was a long section which went unexamined about the importance of inquiry-based learning which is not my cup of tea. The continued emphasis on the need to establish clear goals from practical work is certainly something which I think is important.

SCORE framework for planning practicals

This framework for planning practicals builds on the ideas above. I found there to be a number of assertions which I do not believe to be supported by the evidence. One was that “learning is very often more effective when it incorporates hands-on experience,” I would need to see a proper RCT before I could subscribe to that.

I don’t think anyone would disagree with this statement “The quality of practical work experiences should be judged by the progress students make in their learning and measured against agreed success criteria.” but the problem is the “success criteria.” In part 3 I point to the lack of evidence supporting “critical thinking” courses. My understanding (and follow the links on that page) based on the evidence is that these courses tend to be very good at improving scores on the measures which they have devised but not much else. I have linked here to a number of journals which reference randomised control trials to assess impact on learning of various interventions – in my opinion these should be given more weight.

It also continues to promote enquiry based learning:

“Some High quality practical work will include:

• Self-directed enquiry by individuals, or more commonly by groups, which promotes ‘pupil ownership’ of their science and can be motivating and enjoyable.

• Investigations to encourage team-work with members being given particular roles in the planning, implementing, interpreting and communication of the work.

• Extended enquiry or projects which encourage pupil autonomy and opportunities for decision making.

• Challenges to existing ideas and established concepts: a stimulating demonstration can prompt pupils’ thinking – ‘brains-on’ accompanying ‘hands-on’ experience.”

It will come as no surprise to you that I don’t much like the first four bullet points here. I do like the fifth; Willingham writes that conflict is at the heart of all great explanations.