Does year-round schooling improve academic performance?
The short answer is no—at least not in a clear, consistent way. A large study comparing fifth graders' reading and math scores across three school years (2016–2019) found no statistically significant difference between year-round and traditional calendar schools [4]. That means, on average, students performed about the same regardless of which calendar they followed. Another study in Arkansas, which looked at districts that adopted year-round calendars after a 2021 state law, actually found negative and statistically significant results for student literacy growth compared to traditional calendars [5]. So the evidence does not support the idea that year-round schooling boosts academic achievement.
What about physical health and weight gain?
Here the picture is more nuanced. Two studies from the same research group tracked children's body mass index (BMI) and cardiorespiratory fitness (CRF) over two summers. They found that children in year-round schools gained less BMI during summer breaks—about 0.15 to 0.16 fewer BMI points each summer compared to traditional school children [1][2]. This is likely because year-round calendars have shorter, more frequent breaks, reducing the long unstructured summer vacation where kids tend to gain weight. However, during the school year itself, year-round students actually gained more BMI than traditional students, so the overall effect from kindergarten through sixth grade was similar for both calendars [2]. For fitness, year-round students improved their cardiorespiratory fitness more during summer (about 0.4 to 0.8 more laps on a running test per month) but lost ground during the school year [1][2]. So year-round schooling may help prevent summer weight gain, but it doesn't produce a lasting overall health advantage.
Who benefits most from year-round schooling?
The health benefits appear strongest for certain groups. One study found that the protective effect against summer BMI gain was especially pronounced for children who were overweight or obese, and for Black children [2]. This makes sense because these groups are at higher risk for accelerated summer weight gain in traditional calendars. The structured environment of year-round school—with regular physical activity and meal schedules—seems to help these children maintain healthier weight during what would otherwise be a long, unstructured summer. For academic outcomes, no specific group was identified as benefiting more, since the overall academic results were neutral or negative [4][5].
Sources used in this answer
The potential of a year-round school calendar for maintaining children's weight status and fitness: Preliminary outcomes from a natural experiment.
Year-round students gained less BMI (difference of -0.44) and less cardiorespiratory fitness (difference of -1.92 laps) overall compared to traditional students, but the benefit was mostly during summer and reversed during the school year.
Impact of a year‐round school calendar on children's <scp>BMI</scp> and fitness: Final outcomes from a natural experiment
Children in year-round schools gained less BMI monthly during summer (difference of -0.029 zBMI) and more CRF (difference of 0.834 laps), but gained more BMI during the school year; overall growth from kindergarten to sixth grade was similar between calendars.
Impact of a year-round school calendar on children's BMI and fitness: Final outcomes from a natural experiment.
Same study as paper 2, confirming that structured summer programming may mitigate accelerated summer BMI gain and fitness loss, especially for overweight, obese, or Black children.
Impact of School Calendar on Academic Performance: A Comparative Study of the Year-Round and Traditional Calendars
No statistically significant differences in fifth-grade reading or math scores were found between year-round and traditional calendar schools across three school years (2016–2019).
Exploring Academic Outcomes in Arkansas Schools: A Study of Four-Day School Week and Year-Round Calendar Districts
Arkansas districts that adopted year-round calendars experienced negative and statistically significant results in student literacy growth compared to traditional calendar districts.