Students who take course modules in the largest groups are likely to get lower grades, particularly in science, technology, engineering and maths subjects, a new study suggests.

Researchers looked at data on grades and module enrolments from about 25,000 first-year undergraduates across seven years at a large UK research-intensive university?to see if there was any link between class size and performance.

After controlling for student ability by statistically isolating how a certain student fared as class size varied, they found that the bigger the group on a module, the lower their grades.

The effect was even more pronounced for STEM modules, while a separate analysis also suggested that students from the most disadvantaged backgrounds tended to suffer more from larger classes.

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, published in the?Economics of Education Review,?the authors say that their findings have ¡°important implications¡± for the current focus of many governments on STEM in higher education.

Although it ¡°might seem obvious¡±, the findings suggest ¡°the drive to expand enrolment in STEM subjects should be accompanied by investment in teaching resources to avoid a deterioration in students¡¯ achievement¡±.

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¡°Our analysis highlights that the negative effects in STEM subjects would be more pronounced than in non-STEM subjects, suggesting that there might be a need to funnel scarce resources in the STEM direction.¡±?

They add that the data on disadvantaged students also suggests ¡°developments that would lead to higher student to staff ratios in these fields would disproportionately impact a group that is already disadvantaged in its access to tertiary education¡±.

Although the paper does not fully investigate why larger classes have a particular impact on STEM students, it refers to previous research highlighting the instructional nature of such subjects ¨C rather than the student-centred model of learning employed in non-STEM disciplines ¨C and how this could be a reason for the difference.

Data for the study were taken from first-years studying from 2007-08 to 2013-14, but co-author Michael Vlassopoulos, professor of economics at the University of Southampton, added that an interesting area for further research would be how variations in class sizes might have affected student performance during the pandemic.

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¡°We know relatively less about how staff-student ratios impact learning in online settings, although some research on this is now emerging due to the pandemic. Certainly, [this is] an area where more research is needed going forward,¡± he said.

simon.baker@timeshighereducation.com