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Version 1.2 – Updated June 2023

Modifying school calendars / timetables


  • Influence: Modifying school calendars / timetables
  • Domain: School
  • Sub-Domain: Types of schools
  • Potential to Accelerate Student Achievement: Likely to have a small positive impact
  • Influence Definition: This includes changing the school terms, semesters, vacation times, times of day for starting and closing school, block scheduling or various time spans for classes.


  • Number of meta-analyses: 2
  • Number of studies: 77
  • Number of students: 44,000
  • Number of effects: 674
  • Weighted mean effect size: 0.11
  • Robustness index: 3


Journal Title Author First Author's Country Article Name Year Published Variable Number of Studies Number of Students Number of Effects Effect Size
Campbell Collaboration Fitzpatrick & Burns USA Single-track year-round education for improving academic achievement in US K-12 schools: Results of a meta-analysis. 2019 Year round schooling 30 0 30 0.13
Review of Educational Research Cooper, Valentine, Charlton & Melson USA The effects of modified school calendars on student achievement and on school and community attitudes. 2003 Modified school calendar vs. traditional calendar 47 44,000 644 0.09
TOTAL/AVERAGE 77 44,000 674 0.11
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