The Shrinking School Year

What You Should Know

Children across the country are missing more school than at any time in recent memory, particularly compared with levels seen before the COVID-19 pandemic. Chronic absenteeism has roughly doubled since before the pandemic. Nearly one in four American students — roughly 12 million children — are now chronically absent, and average daily attendance (ADA) has fallen across the board (Appendix).

This crisis is compounded for individual students. If a student misses just 10 days of school every year, they will lose over half a year of instruction by the time they finish high school. If they are chronically absent, their lost days add up to a full year of instruction they will never get back — and maybe more.

Note: To be labeled as chronically absent, a student must miss 10% of the school year, or about 18 days.

Beyond student absences, school years are quietly being shortened. In some districts, when strikes, weather days, holidays, and professional development are combined, students may lose several weeks of instruction that never appear in any absenteeism statistic. 

The toll of these missed days? Declining student achievement. National Assessment of Educational Progress (NAEP) results show that students are learning less. Twelfth-grade reading scores are 10 points lower than when the test was first administered in 1992 — more than a 30-year backslide.

Parents, school board members, district administrators, policymakers, and advocates should see this crisis as a call to action: ask questions and push for change.  

A Portrait of Missed Days: Student Profiles

America’s K-12 students are missing more school than ever before. The consequences of that are showing up in their academic performance, their life chances, and the nation’s economic future. Since the COVID-19 pandemic disrupted schooling in 2020, student attendance has not recovered.¹ Chronic absenteeism has nearly doubled.² ADA has fallen across the board.³ And test scores are the worst they have been in decades.⁴

While these changes are alarming for America’s students on a national scale, they are staggering for individual students — even those who do not miss many days themselves. To better understand the impact on young people, four illustrative student profiles capture potential days missed in one school year and track how those missed school days add up to significant missed learning by the end of high school.  

The Academic Toll of Absenteeism

Recent NAEP data provide the clearest window into what all this missing time is costing students academically. Reading scores for 4th and 8th grade in 2024 dropped five points from 2019 levels,⁵ continuing a downward trend that predates COVID-19. About one-third of 8th graders are now failing to hit even the “basic” benchmark in reading, the largest percentage ever recorded. Forty percent of 4th graders are working below the basic level in reading, the highest rate since 2002.⁶ Eighth-grade math scores are eight points below 2019 levels and have shown no meaningful recovery since 2022.⁷

The picture is even more sobering for high schoolers. In 2024, 12th-grade math scores were the lowest since 2005, and 45% of high school seniors scored below the “basic” achievement level in math — the highest such percentage ever recorded.⁸ The average 12th-grade reading score is 10 points lower than when NAEP was first administered in 1992.⁹ Only about one-third of high school seniors are academically prepared for college-level math, down from 37% in 2019.¹⁰

NAEP Scores in Context

Roughly translating these scores into practical terms,¹¹ the eight-point drop in 8th-grade math scores equates to more than a half-year of lost schooling for the average student. Researchers at McKinsey & Company found that students tested in 2021 were about 10 points behind in math compared with matched students in prior years,¹² equivalent to roughly four months of lost learning in math alone. And as of fall 2024, only one in three schools had recovered to pre-pandemic achievement levels in math or reading, while just one in seven had recovered in both.¹³

The NAEP data also include striking findings about attendance: Nearly one-third of 12th graders reported missing three or more days of school in the month prior to taking the 2024 assessment,¹⁴ a substantial increase from 2019. And absenteeism levels across all NAEP-tested grades (4th, 8th, and 12th) remained markedly higher in 2024 than before the pandemic.¹⁵

Consequences Beyond the Classroom

The effects of this missed learning are not temporary, and they are already showing up on college campuses. Research projects that the pandemic’s academic disruptions will result in lower adult earnings and reduced postsecondary attainment for the cohorts most affected.¹⁶ And the field has long known that students who are chronically absent are significantly more likely to drop out of high school — an experience strongly associated with higher unemployment, lower wages, and greater risk of housing instability.¹⁷ What is different today is the scale: Millions of students are on this trajectory simultaneously, and the consequences are no longer hypothetical. Those consequences have been slow to surface in part because the K-12 system has absorbed them quietly, through lowered cut scores on state assessments,¹⁸ the widespread adoption of test-optional and test-free college admissions,¹⁹ and pandemic-era grading and promotion practices that allowed students to move forward without the same evidence of mastery.²⁰

These policy choices are understandable responses to a genuine crisis, but they defer rather than resolve the problem. Students arrive at college or the workforce carrying knowledge gaps that were never addressed, and institutions without the same flexibility to lower the bar are left to confront those gaps directly. At the University of California, San Diego, for example, nearly 12% of the fall 2025 incoming freshman class enrolled in remedial math, with knowledge gaps stretching back to middle school — a deterioration the university attributed directly to the pandemic.²¹ Before COVID-19, remediation rates at community colleges nationwide were already approaching 70%, and there is every reason to believe those rates are climbing.²² What is accumulating in classrooms across the country is the downstream consequence of years of missed instruction, and the students least able to withstand those losses are the ones bearing most of them.

This crisis does not just affect the students who are missing the most school days. Research shows that students in classrooms with high rates of chronic absenteeism see lower academic outcomes even if they are present every day.²³ When a significant share of a child’s class is absent on any given day, instruction is disrupted, teachers slow down, and everyone loses. Missing school is not just an individual problem; it is a collective one. 

Post-Pandemic Attendance 

Before the pandemic, roughly 15% of K-12 students were chronically absent, meaning they missed 10% or more of the school year, or about 18 days. That figure rose sharply to nearly 30% in school year (SY) 2021-22. Despite modest improvement, chronic absenteeism remained at approximately 24% in SY23-24.²⁴ That means nearly one in four American students — roughly 12 million children — are now missing enough school to put their academic trajectory at serious risk. Before the pandemic, that number was closer to one in seven.

The scale of this loss is staggering. With approximately 50 million K-12 students and a typical 180-day school year, the U.S. system generates roughly 9 billion possible student days of instruction annually. Research consistently shows that ADA remains about 2 to 3 percentage points below pre-pandemic levels in many states.²⁵  A 1-point drop equals 90 million fewer student days attended. Taken together, chronic absenteeism and broader attendance declines add up to an estimated 200 to 300 million more student days lost per year than before 2020. Even using conservative assumptions, that means the American school system is delivering nearly a week less instruction per child, every single year.²⁶

Put another way, if a child misses just two additional weeks of school every year, over a 13-year K-12 career that adds up to more than half a school year of lost instruction. For the millions of students who are chronically absent, the accumulated deficit is catastrophic: Missing 18 days a year over 13 years adds up to 234 days of missed school — more than a full year of instruction, gone.

The Quiet Shrinking of the School Year

Even if students attend school reliably, their school year is being quietly shortened. Every missed learning day adds up. And in district after district across the country, the causes are multiplying. Below are the kinds of disruptions that are now routinely pulling kids out of the classroom, often without parents fully realizing how much accumulates over a single school year.

Teacher Strikes

Teacher strikes can erase weeks of instruction in a single school year. A comprehensive study by researchers at Brown University and the University at Albany documented 772 teacher strikes between SY07-08 and SY23-24, generating 48 million missed student days — a sustained pattern of labor disruption that touched school districts in nearly every region of the country.²⁷ The movement peaked with the nationwide Red for Ed wave in 2018, the largest work stoppage in a generation: West Virginia teachers shut down schools in all 55 counties for nine days, affecting roughly 250,000 students;²⁸ Oklahoma teachers followed with a nine-day walkout that closed districts across the state;²⁹ and Arizona teachers staged a six-day statewide walkout.³⁰ It did not stop there. Portland, Oregon’s first teacher strike in November 2023 canceled 11 full days of instruction for more than 45,000 students.³¹ The Los Angeles Unified School District strike in March 2023 forced 430,000 students to stay home for three days.³² Minneapolis teachers went on strike for nearly three weeks in 2022.³³ In each case, school closures stacked significant instructional losses on top of already-elevated absenteeism.

Natural Disasters and Severe Weather

Pre-pandemic research documented approximately 91.5 million student days lost to prolonged unplanned school closures from 2011 to 2019, averaging about 11 million student days per year. The main drivers were natural disasters (47%) and adverse weather (35%).³⁴ 

Students in storm-prone regions such as the Gulf Coast, the mid-Atlantic, and the Southeast face regular multiday closures from hurricanes, ice storms, and flooding. For a family in coastal North Carolina or Houston, a single bad hurricane season can erase a week or more of school in a single year. In 2024, two major hurricanes closed schools across Florida and North Carolina for extended periods.³⁵

Moreover, wildfire smoke and extreme heat are now among the fastest-growing sources of lost instructional time in the country. A 17-year analysis of California schools found that wildfire closures accounted for nearly two-thirds of all emergency school closure days in the state, and losses of 10 or more school days to wildfire, virtually unheard of before 2015, have since occurred hundreds of times.³⁶ In January 2025, the Los Angeles wildfires destroyed at least a dozen K-12 schools and caused widespread closures affecting hundreds of thousands of students.³⁷

Extreme heat is also forcing closures in the Midwest and Northeast, as well as in the South and Southwest. In September 2023, a late-summer heat wave forced school closures and early dismissals in districts from Milwaukee to New York City.³⁸ 

While there is no comprehensive national data set comparing recent school closures with pre-pandemic levels, broader climate trends suggest severe weather events are an increasingly common driver of school disruptions. In 2023, the U.S. experienced 28 separate weather disasters that each caused at least $1 billion in damage, the highest number of billion-dollar events ever recorded in a single year and nearly triple the historical average.³⁹ The five-year average (2020-2024) is now 23 billion-dollar weather disaster events per year, more than double the historical average of nine per year.⁴⁰ If weather-related closures have increased by even 10% in the post-pandemic period, that would amount to an additional 1 to 2 million student days lost annually.

Crowded School Calendars

American public schools are observing more religious holidays than ever before, driven by well-intentioned efforts to be inclusive of diverse student populations. New York City added four days off to its SY23-24 school calendar following community pressure,⁴¹ including additional days for Passover, Eid al-Adha, and Easter. This decision reduced the total instructional days for the year from 182 to 178. The pressure to expand school calendars is spreading. Pennsylvania, Connecticut, and California have all passed laws in recent years recognizing Diwali as a state holiday, and advocates are pushing for more.⁴² Though some districts have managed to add holidays without reducing instructional days (e.g., by rescheduling teacher professional development days), others are simply subtracting the days, quietly shortening an already compressed school year. 

Standardized testing adds further pressure. A 2023 Government Accountability Office report found that students in traditional public schools spent an average of 16 days taking standardized tests in a single school year, with some districts reporting figures as high as 27 days for 11th graders — nearly 15% of the school year.⁴³ Those figures count only the days spent taking tests, not the surrounding weeks of test preparation, logistics, and administrative disruption that further compress the time available for instruction.

City Celebrations 

Across the country, school districts regularly cancel classes when local sports teams win championships. When the Kansas City Chiefs won the Super Bowl in 2023 and 2024, school districts in the region canceled classes for the victory parades.⁴⁴ When the Philadelphia Eagles won the Super Bowl in 2025, the School District of Philadelphia and at least one nearby district closed for the parade.⁴⁵ When the Boston Celtics won the NBA championship in 2024, Boston Public Schools closed for the victory parade, effectively ending the school year a day early for more than 50,000 students.⁴⁶ These decisions are often celebrated, and any given day, taken in isolation, may feel inconsequential. But each is one more day subtracted from an already shrinking instructional year.

Other Culprits of Lost Instructional Time 

The estimates in this brief are deliberately conservative. They count days when school is closed or students are absent. They do not count the substantial instructional time lost on days that officially count as school.

In a case study of Providence, Rhode Island, researchers at Brown University and Stanford University found that high school students lost roughly one-quarter of their daily instructional time to things such as teacher absences, intercom announcements, and other in-school disruptions on days that officially counted as school. Middle and elementary schoolers lost 21% and 16% of their instructional time, respectively, to the same kinds of disruptions. For the average Providence high schooler, that added up to nearly 100 hours of lost instruction over the course of a year.⁴⁷ Providence was chosen for the case study in part because it had elevated absenteeism rates, and its numbers may not be typical of every district. But the categories of disruption the researchers identified, including teacher absences, administrative interruptions, and students pulled from class, are universal. And even that estimate likely understates the true scale of lost learning time, because it captures only disruptions visible in the Providence data, not the many ways instructional quality erodes even when students are physically present and class is technically underway.

Among the things this analysis cannot count: 

• Substitute Teachers: Before the pandemic, teachers missed an average of nine to 11 days per school year, already enough to meaningfully disrupt instruction.⁴⁸ Since the pandemic, the problem has grown: Seventy-two percent of schools reported that chronic teacher absenteeism has increased compared with pre-pandemic levels,⁴⁹ and research has consistently found that students learn less when their regular classroom teacher is absent.⁵⁰
• Lockdown Drills and Safety Events: Schools are required to conduct regular lockdown, fire, and emergency drills. A drill that runs long can effectively end a school day’s instructional arc even when no one is sent home. 
• Pep Rallies, Field Days, Spirit Weeks, and Seasonal Events: These are legitimate parts of school culture, but on days when the afternoon is given over to a pep rally or field day, meaningful instruction often winds down in the morning in anticipation. 
• Late Starts and Early Dismissals: Days that begin with a two-hour delay or end with an early release may appear on the calendar as full instructional days but deliver a fraction of normal learning time. 
• End-of-Year Disengagement: Calendar days are a crude proxy for learning time. Research distinguishes between time formally allocated for school and the smaller amount of time converted into active instruction.⁵¹ That distinction is especially relevant late in the year, when state testing, end-of-year activities, and administrative demands can reduce the instructional intensity of days that still count fully toward annual seat-time requirements.

Taken together, even students who attend every scheduled day of school, in a district with no teacher strikes or unforeseen closures, are receiving substantially less instructional time than the official calendar suggests. The estimates in this brief almost certainly understate the true erosion of learning time that American students are experiencing.

The Limits of Remote Learning and Other Alternatives

Some might argue that a reduced in-person school year is not a problem at all but rather a welcome evolution. Students today have access to tools that did not exist a generation ago, including recorded lessons, online tutoring platforms, digital homework, and in some districts, full virtual school options. If a student misses a day but watches the lesson that night, does the absence still carry the same cost? 

The Pandemic Test Case

The evidence says yes. The most direct test of this proposition came during the pandemic itself, when American schools carried out the largest and most rapid expansion of remote and hybrid learning in history — and the result was the worst academic decline in decades. Average learning loss during SY20-21 was roughly half a year in math and one-third of a year in reading, with the steepest losses among the students who had the least reliable access to in-person instruction.⁵² Those losses have persisted. As of fall 2024, only one in three schools had returned to pre-pandemic achievement levels in math or reading, and just one in seven had recovered in both.⁵³

The broader research on full-time virtual schooling tells the same story. The National Education Policy Center, which has tracked publicly funded K-12 virtual schools annually since 2013, concluded in its most recent comprehensive report that virtual school performance remains poor and that little if any research supports the claimed benefits of virtual schooling; the center notes this finding has changed very little over the decade it has been studying the question.⁵⁴

Research on homework points in the same direction. Homework can have modest positive effects on achievement, particularly for older students, but the evidence is weaker for younger students and varies by context — making it a limited substitute for direct instructional time.⁵⁵

Where the Alternatives Fall Short

The research on tutoring and summer programs is more promising, but with important caveats. High-dosage tutoring, when delivered consistently during the school day, has shown meaningful gains: A University of Chicago Education Lab study found that in-school tutoring led to large positive effects in math,⁵⁶ and a meta-analysis of 89 tutoring studies found gains equivalent to roughly three to four months of additional learning for early elementary students.⁵⁷ Summer programs show more modest results. Studies of programs offered across 10 large districts in 2022 and 2023 found small positive effects on math scores but no measurable impact on reading.⁵⁸ A meta-analysis of 37 experimental studies found that summer math programs produced real but modest gains — roughly equivalent to an extra week or two of learning — well short of what would be needed to offset a year or more of accumulated absences.⁵⁹

The deeper problem is scale and participation. For example, when New Mexico moved its tutoring program from evenings and weekends into the school day, participation and attendance rates improved substantially.⁶⁰ That finding underscores the issue — interventions designed to compensate for missed school work best when students are in school to receive them. When Nashville tried to scale high-dosage tutoring districtwide, the results were largely disappointing: Tutoring delivered to nearly 7,000 students produced limited effects in reading and no discernible effects in math.⁶¹ The interventions that work in controlled studies frequently underperform when deployed at scale, to the students who need them most, in the conditions that exist.

None of this means that tutoring, summer programs, or other alternatives have no value in curbing learning losses. They can and do serve students in specific circumstances, and continued investment in well-designed versions of these programs is worthwhile. But the data accumulated since 2020 make a strong case that they are not functioning as a substitute for regular in-person attendance at the scale required. If those alternatives were compensating for the surge in absenteeism, achievement scores would be stable or recovering across the country. They are not. The question is not whether other modalities can theoretically deliver learning; it is whether they are doing so for the millions of students now missing significant amounts of school. The evidence, so far, says this is not the case. 

The Path Forward

The calendar disruptions documented in this brief are largely system driven. But running alongside them is a quieter, harder-to-measure shift in how students and families think about individual absences. The threshold for staying home has slackened. The pandemic forced families to weigh illness risk in genuinely new ways, and for many, that recalibration never fully reversed. At least 12 states have now formalized this loosening by designating mental health days as excused absences.⁶² But the cumulative effect is a culture in which being in school has become more optional than it has ever been. Each individual’s decision to stay home is defensible. In the aggregate, these decisions represent a structural shift in attendance with real consequences for student learning.  

The goal is not to eliminate every disruption — that would be neither possible nor desirable. It is to make these trade-offs visible, deliberate, and understood. Every day of school matters. The students who can least afford to miss school are bearing most of these losses. The first step toward doing better is knowing what is actually happening.

While the data in this brief are national estimates, not a verdict on any single school or district, they are clear: American students are attending school significantly less than they were before the pandemic, the trend shows no sign of reversing, and the academic consequences are already visible in the worst national test scores in a generation.⁶³ Children cannot master reading, math, science, and critical thinking if they are not in the building. Every intervention — every tutoring program, every curriculum reform, every teacher training initiative — requires a child to be present for it to be effective. Missing school is not a neutral act. It is a compounding cost, paid across an entire educational career.

The data do not point to a single lever. But they do suggest questions worth asking. 

Questions to Consider 

For Policymakers and Advocates:

• Do current accountability frameworks measure instructional days delivered and ADA, or only chronic absenteeism rates? 

• In decisions about mental health days, extended breaks, and unplanned closures, is cumulative impact being assessed — not just whether any single closure is reasonable, but what it means in the context of everything else? 

• Are attendance recovery efforts addressing both sides of the equation: whether students are showing up, and whether the school year calendar they are being asked to attend is itself consistent and coherent? 

For School Board Members and District Administrators:

• How does your current school calendar compare to SY18-19? Has the number of disrupted weeks increased, and if so, was that a deliberate policy choice or the result of incremental decisions made without a formal review? 

• How many “isolated days” — single-day breaks or closures not adjacent to weekends or holidays — appear on your calendar, and have they been evaluated for consolidation? 

• Does your district assess the cumulative instructional impact of calendar decisions before they are made, or only the individual rationale for each one? 

• Is your calendar disruption data published alongside attendance data, so families and board members can see the full picture of instructional time delivered? 

For Parents and Community Members:

• What is your school district’s ADA rate, and how has it changed since SY18-19? 

• How many full five-day instructional weeks does your district’s calendar actually contain? 

• How does your district ensure that days students are present are high-quality instructional days and not just days counted toward attendance? 

• When a teacher is absent, what happens to instruction? How are substitute teachers recruited, trained, and supported?