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.