As early as the 4th grade, girls perform better than boys on standardized tests in reading and writing, and as they get older that achievement gap widens even more, according to one study. While the tests showed that girls, in general, scored significantly higher than boys in both reading and writing in the fourth grade, that gap widened further in eighth and 12th grades, and the difference was far more substantial for writing than it was for reading. The authors offered several theories to explain the findings. For instance, boys are statistically more likely to have a learning disability and they may also face peer pressure to conform to masculine norms, which could cause them not to make reading a priority.
Reilly, D., Neumann, D. L., & Andrews, G. (2018). Gender differences in reading and writing achievement: Evidence from the National Assessment of Educational Progress (NAEP). American Psychologist. http://dx.doi.org/10.1037/amp0000356