A research synthesis conducted by Cooper et al. (1996) integrated 39 studies examining the effects of summer vacation on standardized achievement test scores. The 39 studies included 13 that could be included in a meta-analysis (a statistical integration) of the results. The meta-analysis indicated that summer learning loss equaled at least one month of instruction as measured by grade level equivalents on standardized test scores-on average, children’s tests scores were at least one month lower when they returned to school in fall than scores were when students left in spring.
The meta-analysis also found differences in the effect of summer vacation on different skill areas. Summer loss was more pronounced for math facts and spelling than for other tested skill areas. The explanation of this result was based on the observation that both math computation and spelling skills involve the acquisition of factual and procedural knowledge, whereas other skill areas, especially math concepts, problem solving, and reading comprehension, are conceptually based. Findings in cognitive psychology suggest that without practice, facts and procedural skills are most susceptible to forgetting (e.g., Cooper & Sweller, 1987). Summer loss was more pronounced for math overall than for reading overall. The authors speculated that children’s home environments might provide more opportunities to practice reading skills than to practice mathematics. Parents may be more attuned to the importance of reading, so they pay attention to keeping their children reading over summer.
In addition to the influence of subject area, the meta- analysis indicated that individual differences among students may also play a role. Among those examined in the studies used in the meta-analysis, neither gender, ethnicity, nor IQ appeared to have a consistent influence on summer learning loss. Family economics was also examined as an influence on what happens to children over summer. The meta-analysis revealed that all students, regardless of the resources in their home, lost roughly equal amounts of math skills over summer. However, substantial economic differences were found for reading. On some measures, middle-class children showed gains in reading achievement over summer, but disadvantaged children showed losses. Reading comprehension scores of both income groups declined, but the scores of disadvantaged students declined more. Again, the authors speculated that income differences could be related to differences in opportunities to practice and learn reading skills over summer, with more books and reading opportunities available for middle-class children (see also Alexander, Entwisle, & Olson, in press).