By: Grace Donaghy
For decades, the American school calendar has followed a familiar pattern: students attend school for most of the year, take a long summer break, and return in the fall. While this structure is deeply familiar, it is not the only way to organize education. Around the world, many different types of learning calendars are in place. Even within the United States — in states like California and North Carolina — schools are beginning to experiment with new approaches to how students spend their time.
This raises a much bigger question: Are American schools making the most effective use of the time students spend learning? Or can we learn from other countries and adapt a new schedule to better our education?
The 2009 PISA Results
One useful starting point is the Programme for International Student Assessment, or PISA, which evaluates the reading, mathematics, and science abilities of 15-year-old students internationally. The 2009 PISA results provide an interesting comparison between the United States and Singapore. Singapore scored 562 in mathematics, 526 in reading, and 542 in science, while the United States scored 487 in mathematics, 500 in reading, and 502 in science (OECD, 2011). This gap has remained substantial, particularly in mathematics, where the difference between the two countries has grown considerably. In PISA 2022, Singapore scored 575 in mathematics, 543 in reading, and 561 in science — the highest average scores of any participating education system in all three subjects. The United States scored 465 in mathematics, 504 in reading, and 499 in science.
The decline in U.S. mathematics performance is particularly worth examining. The OECD reported that the 2022 U.S. mathematics results were among the country’s lowest ever measured by PISA, while reading and science remained relatively stable compared with 2018 (OECD, 2022). This raises the question of what we’re doing wrong — and what Singapore is doing right.
However, these results do not prove that Singapore’s school calendar or schedule causes its higher scores. Education systems differ in curriculum, teacher preparation, culture, family involvement, tutoring, assessment, and many other factors. Instead, the difference provides an opportunity to ask a more useful question: What can the United States learn from the way other countries structure students’ time?
Looking Beyond the School Calendar
Even within the United States, school calendars are structured differently. While the traditional calendar typically places a long summer break between two semesters, some states and districts have experimented with year-round and modified calendars that distribute breaks more evenly throughout the year. California, for example, identifies several year-round models, including 45/15, 60/20, 90/30, and Orchard calendars (CDE, 2025). All of these calendars have the same number of instruction days; they simply divide them differently, with smaller breaks spread throughout the year. North Carolina also permits both single-track and multitrack year-round calendars, but state law gives local boards of education authority over the school calendar (N.C. Gen. Stat. § 115C-84.2). This means that even within the same state, communities can make different decisions about how to structure students’ instructional time.
Does calendar structure actually affect how students learn and perform on tests? Logically, there’s good reason to think it should. The “summer slide” occurs over long breaks, when students aren’t in school and lose fundamental math and reading skills. Research has estimated that students can lose roughly a month of learning in math and reading over the summer, with some evidence that losses can be larger for economically disadvantaged students. This has led some educators and policymakers to consider whether shorter summer breaks and more frequent breaks throughout the year could help students retain what they’ve learned.
However, the evidence becomes much less clear when looking at whether changing the school calendar actually improves academic achievement. A 2019 meta-analysis found that single-track year-round schooling was associated with modestly higher average math and reading achievement, but found no differences in proficiency rates. Another major study using mandatory calendar changes in Wake County, North Carolina, found essentially no effect on average academic achievement from switching to year-round schooling (AEA, 2012). Together, these findings suggest that the school calendar may influence how students experience breaks and maintain learning, but simply rearranging the school year does not guarantee better academic outcomes. The number and timing of school days may matter, but they’re only one part of a much larger education system.
The evidence on school calendars alone doesn’t provide a simple answer. Instead of asking whether the United States should shorten summer vacation or adopt year-round schooling, it may be more useful to examine how successful education systems use students’ time as a whole. Singapore provides an especially useful comparison, given its consistently high international assessment performance and its different approach to organizing education.
The United States vs. Singapore
In PISA 2022, 92% of Singaporean students reached at least Level 2 proficiency in mathematics, compared with 69% across OECD countries. Additionally, 41% of Singaporean students were top performers in mathematics, compared with only 9% across OECD countries (OECD, 2022). These results make Singapore an interesting comparison for the United States. However, Singapore’s success cannot be attributed to one factor, such as a particular school calendar or longer school day. Instead, Singapore has developed an education system that places a strong emphasis on structured instructional time, teacher support, differentiated learning, technology, and opportunities beyond traditional academic subjects.
One major difference is the amount of time students spend in formal instruction. According to the OECD’s PISA 2022 data, Singaporean students reported approximately 29 hours per week in regular language-of-instruction lessons, placing Singapore among the countries with the longest instructional time in this category. Singaporean students also reported spending approximately two hours per day on homework — relatively high compared with other OECD and partner education systems. This is an important distinction from the argument that “more school automatically produces better results.” The research does not show that simply increasing instructional hours causes higher achievement. In fact, Singapore’s high achievement exists alongside many other features of its education system. The lesson for the United States, then, is not to simply make the school day longer, but to make better use of the hours students are already there.
Another important feature is the amount of support students receive from teachers. PISA 2022 found that 77% of Singaporean students reported that their mathematics teacher shows interest in every student’s learning, compared with 63% across OECD countries. Additionally, 86% reported that their math teacher gives extra help when students need it, compared with 70% across the OECD. This suggests that Singapore’s approach isn’t simply about putting students in classrooms for more hours — the quality of the interaction during those hours matters.
Singapore has also increasingly moved toward more flexible and personalized learning. Its education system has introduced Full Subject-Based Banding, allowing secondary students to take different subjects at different levels based on their strengths, interests, and learning needs. This moves away from the idea that every student must learn every subject at exactly the same level and pace.
Technology is another part of this shift. Singapore has invested heavily in digital learning, including the Singapore Student Learning Space, a national online learning platform. Since the end of 2022, secondary schools and pre-university institutions have incorporated regular Home-Based Learning days into their schedules. These days give students opportunities to organize portions of their own learning while still receiving guidance and support from teachers. Students who need additional support can also return to school on these days.
What Could the United States Adapt?
Rather than simply extending the American school year or eliminating summer vacation, the United States could consider incorporating some of the practices Singapore uses to make learning more targeted and personalized.
Schools could strengthen individualized academic support. Singapore’s high level of reported teacher assistance suggests that students benefit when teachers have the time and resources to provide help when it’s needed. My own school provided opportunities for this type of support by requiring teachers to be available in their classrooms for an hour before school each morning to answer questions. We also had an additional 30 minutes of lunch, during which students could sign up to meet with a teacher for extra help. Opportunities like these give students dedicated time to ask questions, clarify difficult concepts, and receive the one-on-one support they may not get during a regular class period. Expanding similar opportunities could help American schools provide more individualized support without necessarily adding more instructional days to the school calendar.
Schools could also provide greater flexibility within individual subjects. Singapore’s subject-based approach demonstrates that students don’t necessarily need to be placed into one overall academic track. An American student could potentially be advanced in mathematics while receiving additional support in English, rather than being labeled simply as “advanced” or “struggling.”
Technology could be used to personalize instruction rather than replace teachers. Singapore’s digital learning shows how technology can allow students to work independently while teachers continue to provide guidance. American schools could use adaptive technology to identify gaps in understanding, provide additional practice, and allow students who have mastered material to move forward.
Schools could also make greater use of time for skills beyond traditional academics. Singapore’s emphasis on communication, collaboration, leadership, civic literacy, and social-emotional development shows how schools can prepare students for life beyond standardized tests. Instead of asking only how many hours students spend on math or reading, schools could also ask whether students are developing the skills they’ll need in college, careers, and their communities.
The United States could focus less on simply increasing instructional time and more on improving the effectiveness of that time. As the research above suggests, changing the school calendar alone does not consistently produce higher achievement. Singapore offers a useful example of what it looks like to combine strong teachers, targeted support, flexible learning, technology, and broader skill development within one organized education system.
The Takeaway
Singapore’s success does not prove that the United States needs a longer school year, fewer breaks, or more homework. Instead, it demonstrates that how schools use students’ time may be just as important as how much time students spend in school. Shortening summer vacation does not automatically produce higher achievement, just as adding instructional hours does not guarantee better results. The OECD’s international comparisons reinforce this point, showing that instructional time alone has a limited relationship with academic performance.
For a country facing declining mathematics performance while education systems like Singapore continue to achieve significantly higher results, the question shouldn’t simply be whether American students need more days in the classroom. It should be whether the traditional structure of the school day is giving students the right opportunities to learn, practice, create, communicate, and prepare for life beyond school.
Rather than simply adding more time, American schools could consider using existing time differently — providing more individualized support, allowing greater flexibility in learning, using technology to personalize instruction, and creating opportunities for students to develop skills beyond traditional academics.
