Studies also show that the magnitude of summer learning loss varies significantly by grade level, subject matter, and family income. Most importantly, research identifies the cumulative effect of summer learning differences as a primary cause of widening in-school achievement gaps between students by family income.
A recent study by Harris Cooper, professor of psychological sciences at the University of Missouri, estimates that summer loss for all students equals about one month on a grade-level equivalent scale.
Summer loss in mathematics
On average, all students regardless of socio-economic status, lose approximately 2.6 months of grade level equivalency in mathematical computation over the summer months. Researchers speculate that summer learning losses in mathematics are similar among lower and middle-income students because all students are less likely to practice math skills outside the formal classroom setting
Summer loss in reading
Family income plays an important role in predicting the magnitude of summer loss in reading. Low-income students experience significant summer learning losses in reading comprehension and word recognition. On average, middle-income students actually experience slight gains in reading performance over the summer months.
Low-income students experience an average summer learning loss in reading achievement of over two months. On average, children from low-income families lose nearly three months of grade-level equivalency during the summer months each year, compared to an average of one month lost by middle-income children when reading and math performance are combined.
Impact on the achievement gap
The research of Johns Hopkins University sociologists Karl Alexander and Doris Entwisle documents that while student achievement for both middle and lower-income students improves at similar rates during the school year, low-income students experience cumulative summer learning losses over the elementary school grades.
In the Beginning School Study, Alexander and Entwisle found that the increasing gap in test scores between children from families of high and low socioeconomic status over the elementary-school period accrued entirely from the differential gains that students made when school was closed.
Poor families could not make up for the resources the school had been providing. Middle-class families could make up for the school’s resources to a considerable extent and so their children’s growth continued, though at a slower pace than during the school year. By the end of fifth grade, poor children fall more than two years behind their middle-class peers in verbal achievement and 1 1/2 years behind in math.