Boys tend to outperform girls in high-stakes science tests, but it is not because they are better students, according to researchers.
The study, published in the journal Plos One, showed that performance gaps between male and female students increased or decreased based on whether instructors emphasised or de-emphasised the value of exams.
"This is not simply due to a 'watering down' of poor performance through the use of easy points," said one of the researchers Sehoya Cotner, associate professor at the University of Minnesota.
"Rather, on the exams themselves, women perform on par with men when the stakes are not so high," Cotner said.
The findings suggest that changing how instructors assess students could help close the achievement gap between male and female students in some science courses.
The results were based on a year-long study of students in nine introductory biology courses.
The researchers found that female students did not under-perform in courses where exams count for less than half of the total course grade.
In a separate study, instructors changed the curriculum in three different courses to place higher or lesser value on high-stakes exams (for example, midterms and finals) and observed gender-biased patterns in performance.
"When the value of exams is changed, performance gaps increase or decrease accordingly," Cotner said.
These findings build on recent research that showed that on average, women's exam performance is adversely affected by test anxiety.
By moving to a "mixed model" of student assessment -- including lower-stakes exams, as well as quizzes and other assignments -- instructors can decrease well established performance gaps between male and female students in science courses, the study added.