One of the intriguing features of the most recent round of PISA results was that practical work seemed to be negatively associated with science understanding. As with all PISA findings, it is not easy to point to a cause and effect relationship but it should at least make us pause.
This week, an open-access study on the effectiveness of practical work was released by a group of physics professors from the U.S. They analysed an interesting data set. Students at three American colleges who were enrolled in a physics course were given the option of attending practical sessions. Some attended these sessions and some did not.
There were systematic differences between the students who chose to attend. They tended to be higher achieving and this is probably linked to the fact that some later engineering courses required attendance. So the researchers completed an analysis that attempted to adjust for this. In the final assessment, the classified questions into two groups; those that related to the practical classes and those that did not. They then computed a difference for each student between their average on each type of question.
They looked at the average ‘difference score’ for the students who attended the practical sessions and for those who did not. There was no statistically significant difference.
So the practical classes appear to have done little to improve the students’ understanding of the concepts involved when compared to concepts not addressed by these classes.
The authors have an explanation for why this might be the case that, in my mind, clearly links to cognitive load theory:
“When one examines the cognitive activities in which students are engaged while completing such lab course activities [12,34], they are dominated by following instructions to collect specified data using unfamiliar equipment, and following specified procedures to analyze the data and write up reports in a specified format. Although the relevant physics concepts were central to the thinking of the instructor that designed and built the experiments, those concepts get little, if any, attention from the student carrying out the assigned activities using that apparatus.”
Of course, practical classes serve a number of purposes. If nothing else, students who aspire to become professional scientists will need to learn to use the equipment. However this finding does cast doubt on the idea that practical work leads to deeper understanding; an idea central to many constructivist approaches to science teaching.
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“Although the relevant physics concepts were central to the thinking of the instructor that designed and built the experiments, those concepts get little, if any, attention from the student carrying out the assigned activities using that apparatus.”
So the “instructor” has done 95% of the work. What a waste.
I suggest this reflects not the futility of practical work but the failure to design good practicals. Their value lies not in demonstrating the ability to followi instructions in the use of equipment but in designing the experiment – that is the intellectual challenge. Which is of course a challenge for instructional designers and a reason why we need more specialised course materials.
Ah, yes. Physics professors, who have been doing this for centuries, just didn’t do it right.
Even if students were given the task of designing an experiment — and an infinite amount of the right equipment was on hand to allow them to do this — they would still not learn any Physics. Because they would need their knowledge of Physics first, or else they could not design a useful experiment. How do you design an experiment about some topic you are ignorant of? Even doctoral students don’t set of with designing their experiment as the first stage, they do a literature search and learn about the topic first — and are usually guided to a topic anyway.
Occam’s razor is much simpler. Practical work is futile to learn any actual science.
I know that in my Chemistry experiments, of which I did many, I never learned any actual Chemistry as a result. That came from lectures. I learned about how some techniques were carried out, how to write up a lab book etc. But no actual Chemistry.
1. I never suggested that anyone can design a Physics experiment without knowing any Physics first – but that after acquiring information, it needs to be practised and applied: memorize, understand, apply – that is the basis of Bloom.
2. It is not within the expertise of Physics professors to design activities in which students can design experiments – structuring that sort of learning activity is a matter of pegagogy, not Physics.
3. Many physics teachers have doubtless been doing it very well at small scale: “how would you go about finding out x?” “what can you infer from these results?” The difficulty is to have this sort of dialogue at scale. Handing out information is easy, of course. But helping people to apply that knowledge is labour intensive.
Thinking that learning science is *just* about absorbing facts leads, I suggest, to the sort of misunderstanding about what science *is* that one hears all too frequently on the BBC. It is a process, not a body of knowledge and being a scientist means having the knowledge and skills to find things out and to question and defend the reliability of those facts.
Does this just suggest that it takes some amount of learning of practical work before procedures and reporting results are sufficiently learned that the student can focus on the physics?
You would have the same problem if you tried to teach physics to someone who hadn’t studied any algebra. You’d find they spent a lot of time trying to follow and reproduce the manipulation of equations rather than understanding the physics.
The fact that practical work takes some attention from students suggests it is non-trivial and time spent on it is time spent learning how to do practical work.
I had one prof who derided high school and undergrad practical work saying it taught students how to reproduce a known result and not explore why they don’t get the right answer. I now thing he was suffering from the curse of knowledge and didn’t appreciate how difficult it is for a novice to do even simple experiments and get reliable answers.
When I started my degree in biochemistry and pharmacology the awful truth dawned on me that professional scientists do practical science ( the bit I didn’t like) all the time. They didn’t get paid to sit and listen to interesting new scientific ideas, which was what I enjoyed doing at school. I was horrified and changed to an arts degree!
My view is that there are three purposes for practical work at this level (secondary through to low-level UG – no opinion after that): learning practical techniques; developing investigative skills; reinforcing conceptual understanding. They require different practical designs. Hopefully I’ve explained myself a bit more clearly here https://dodiscimus.wordpress.com/2017/02/07/young-peoples-view-on-science-education-wellcome-trust-science-education-tracker/
The fault highlighted by the paper is in the first sentence of the abstract:”Instructional labs are widely seen as a… way to teach scientific content.”
Best wishes
Reblogged this on The Echo Chamber.