Reading time: 5-6 minutes
As discussed previously, I’ve been spending a lot of time thinking about practical work of late. I’ve presented most of the below at a few places over the last couple of weeks, including the RSC SaFE National Teachers Conference, and the East Midlands Chemistry Teachers Conference. It seems to be going down well, so I thought I’d summarise here.
I’ve started these discussions with a quick run through of the why of practical work. I think it is important that we think carefully from time to time about why we do practical work, given the expense (in time and cost) and the opportunity costs (could we get to the same learning more effectively another way). I reference the National Curriculum, the Ofsted ‘Maintaining Curiosity‘ report, an OCR longitudinal survey, and some ‘historical’ literature (Hodson, 1990, SSR, 70(256, 33-40). The key point I make is that the reasons teachers seem to state for using practical work hasn’t changed much over the decades, and we’re still questioning how effective it is.
Quotes from the National Curriculum (Slide 5)
- …essential aspects of knowledge, methods, processes and uses of science…
- …curiosity about natural phenomena…
- … explain what is occurring, predict how things will behave, and analyse causes
Quote from ‘Maintaining curiosity’ (Slide 6)
- In the best schools visited, teachers ensured that pupils understood the ‘big ideas’ of science. They made sure that pupils mastered the investigative and practical skills that underpin the development of scientific knowledge and could discover for themselves the relevance and usefulness of those ideas.
Top five reasons identified by teachers for using practical work from the OCR longitudinal study (Slide 7)
- To encourage accurate observation and description
- To develop conceptual understanding
- To develop reporting, presenting, data analysis and discussion skills
- To experience the process of finding facts by investigation
- To develop manipulative skills and techniques
Top five reasons for using practical work, identified in Hodson (1990) (Slide 8)
- Teaching laboratory skills
- Enhancing learning of scientific knowledge
- Insight into and developing scientific method
- Developing ‘scientific attitudes’
I looked at how practical work can be ineffective, and referenced a nice succinct quote from Clackson and Wright (1992, SSR, 74(266), 39-42),
- Although practical work is commonly considered to be invaluable in scientific teaching, research shows that it is not necessarily so valuable in scientific learning. The evidence points to the uncomfortable conclusion that much laboratory work has been of little benefit in helping pupils and students understand concepts.
and posit three key ideas about why practical can be ineffective:
- chemistry is hard
- the practicals used are overloaded
- there is too much to think about.
A brief segue into Johnstone’s triangle follows (Slide 12). I use the context of dissolving table salt, which seems to help get the idea of the triangle across. Interestingly, on asking, I’d say fewer than 20% of teachers were aware of the triangle explicitly (although they may well understand it and have worked it out for themselves implicitly).
Another segue then into the structure of memory, using the model presented in Baddeley’s 2000 paper – I’m aware isn’t the most up-to-date paper and the model has no-doubt moved on, but I’m always concerned about overloading (ironically?) people when talking about these new areas. (Slide 13)
I’ve summarised Cognitive Load Theory via Intrinsic, Extraneous and Germane load as below – again, probably not a full and up-to-date reflection, but I think sufficient to get the idea across, especially when summarised using Greer’s model. (Slide 16):
So practical work can be ineffective because what we’re asking the students to think about is intrinsically hard (lots of abstract and mostly invisible concepts), we’re trying to do too much in the practicals (plan a method, collect data, process the data etc etc etc) and all the domains of thinking overload their capacity to actually think about what we want them to think about, and we end up with a lot of following the recipe, but little learning.
So my ‘Key Questions’ are:
- How do we get beyond them just ‘following the recipe’?
- How do we get them to think?
- How do we reduce the cognitive load inherent in some practical work?
- How do get them thinking about the right stuff?
- How do we maximise the benefit of practical work for our students in our classrooms?
- How can we design practicals that are effective at promoting learning?
and ‘Key Ideas’ are:
- Ensure practicals have a clear goal
- Don’t overload them/students
- Use of microscale activities
- e.g. electrolysis, to reduce extraneous load
- Working up to complex practical tasks
- e.g. titration, to improve instrinic load
How do we make practical work more effective? This is some further hashing out of ideas from over the last couple of weeks. I’ve had the titration ideas out there for a while, but the analysis of the electrolysis has taken my thinking a bit further.
Firstly, looking at extraneous load – the problem of solely written instructions, and how carefully labelled diagrams may be a better method. The key learning of this practical exemplified below would be the observation rather than the ‘ability to follow written instructions’. I was challenged on this one at the East Midlands conference, along the lines of how this would help with exam preparation, and the students needing to know how to write practical methods. My response was on the wider point of not overloading practicals (not everything has to be about exam preparation) and having a clear focus on what is required. If the observation is key, then everything else should be ‘subservient’ to that. (Slide 21)
I then had a go at a Cognitive Load ‘analysis’ – I’m not sure if this is a thing, but it was a useful exercise to demonstrate what students may be thinking about. I used the comparison between electrolysis using the standard Nuffield apparatus, and the microscale copper chloride electrolysis. (Slide 23 and 24)
- application of a current to an aqueous solution of copper chloride produces copper and chlorine
- qualitative tests for chlorine
- charge on ions
- nature of ions in solution
- flow of charge
- formation of metal/covalent substances
- nature of apparatus
- quality of practical instruction
- quality and reliability of equipment
- classroom environment
Doing the full micro-scale practical as written is potentially itself overloaded – far too much to put onto students the first time. (Slide 25)
But this can be easily relieved by leaving out all the ‘indicators’ and building up to them. (Slide 28)
I then went through my ‘breaking down titration‘ – in summary my first teaching of this went straight in with a 20 minute demonstration of titration theory and practice to a Yr11 Triple group and then me expecting them to replicate this with a written method. I was still a very green teacher at this point, and learnt some very valuable lessons. My next attempt was somewhat more nuanced, and led to much better learning – including the use of micro-titration. (Slide 29)
Finally, I discussed an introduction to rates of reaction using simplified kit (£10 2d.p. balanced from Amazon, vinegar from the kitchen cupboard and chalk from the garden). I’m impressed with the quality of the data I managed to get from this, and I think it may be a useful introduction to rates, without having to worry about all the standard kit. (Slide 31 and 32)
Following David Didau’s ‘what if I’m wrong’ motif (having finished ‘What if everything…‘ a couple of months back), I also reference a report by Moreno who neatly summarises some of the concerns about CLT.
- It doesn’t deal with affective factors, including motivation
- Extraneous load may be strongly inter-related with germane load
- There are ambiguous and contradictory studies on the effectiveness of CLT in explaining outcomes.
Summarising with four key bullet points (Slide 37), I reiterated what is for me is a critically important part this – that we continue to think about and discuss our practice, and look to see whether we can improve on what we are doing in the classroom. I don’t particularly mind that I may well be coming to the same conclusions other already have. For me, expanding my personal knowledge and effectiveness is a critical part of my professional development. If I can help others with their’s, then so much the better, and if I can push at the boundaries of the public knowledge, then that’s a bonus.
21/7/17: Rehosted slides and powerpoint on social.ocr.org.uk and indicated specific slides in body of text rather than screenshots.