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A 2012 review of studies on learning time found that the extra time often didn’t produce academic benefits for students and when it did, the benefits were small. Credit: Getty Images

It seems intuitive that what children need now is more time. Because students missed so much instruction during the pandemic, teachers should get extra time to fill all those instructional holes, from teaching mathematical percents and zoological classifications to discussing literary metaphors and American history. 

Indeed, many advocacy groups, including the Learning Policy Institute and Ed Trust, are recommending extending learning time next year. I haven’t heard about many school districts announcing longer schedules yet but I was curious to learn what research evidence shows for students at schools that have extended the day or lengthened the year. (I’m excluding optional after-school programs here.) I was surprised by how few well-designed studies there are and how uncertain the benefits have been. 

”We don’t really know what the effects are,” said Jean B. Grossman, an economist at Princeton University and MDRC, a nonprofit research organization, who has studied this research literature. “My takeaway is that extending the learning year doesn’t really work. Just adding 10 extra days doesn’t seem to have any effect.”

Even advocates of longer school days and years emphasize that extra time by itself often doesn’t have an impact. What you do with the time matters. Devoting the extra time to a daily dose of tutoring seems most promising. But tutoring can work equally well even when the school day isn’t lengthened. Extra time does mean that other activities — from physical education to art and coding — don’t have to be curtailed. Another approach that warrants further study is using the extra time for a double dose of math, in which students take a remedial class and a grade-level class concurrently. That’s worked well in Chicago high schools but not in Miami middle schools. What is clear is that using the extra time for just more hours or more days of traditional instruction doesn’t appear to achieve much.

Lengthening the school day or year isn’t a new idea. The 1983 report A Nation at Risk highlighted how much more instructional time children received in other industrialized nations. Japan had 240 school days and Europe averaged between 190 and 210 days, well above the U.S. average of 180 days. Former President Barack Obama called for increasing learning time and his administration gave almost 1,800 low-performing schools extra money, called School Improvement Grants, to help pay for it. Most chose to lengthen the school day, generally by an hour, above the national average of six and a half hours. But the extra time was coupled with other school reforms, such as teacher evaluations, and it was generally impossible to tell how much the extra time alone was making a difference. 

One of the strongest arguments for longer school days is the record of some high performing charter schools. Rigorous studies have shown impressive academic performance in Knowledge is Power Program (KIPP) charter schools, where students attend school from 7:30 a.m. until 5:00 p.m.. But researchers have been unable to disentangle the extra hours from all the other things that KIPP is doing, from its curriculum to its strict rules, to determine if the longer day is a key to its success. 

One 2012 review of studies on learning time found that the extra time often didn’t produce academic benefits for students and when it did, the benefits were small. “The findings in the literature indicate that simply adding time is insufficient,” the authors at Child Trends, a nonprofit organization, concluded. (The Wallace Foundation, which is among the funders of The Hechinger Report, commissioned this research review.)

The 38 studies in the review that focused on longer days or longer years sometimes found an academic gain for just one group of students, for example, third graders, or for just one subject. One study found higher achievement in science. One didn’t. However, when academic benefits were found, the researchers noticed that low-income and low-achieving students were more likely to reap them.

Sometimes the benefits of extra time are short lived. A full day of kindergarten led to much higher literacy and math skills during the kindergarten year, compared with a half day of kindergarten. But no study found long-term benefits for a full day of kindergarten that lasted beyond first grade. 

Thanks to the Obama administration’s investment in extended learning time, there have been more recent studies. One was a five-year evaluation of a middle school program called Citizen Schools, in which the school day was extended to 6 p.m. Some of the extra time was used for an hour of homework help with volunteer tutors but there wasn’t a structured daily tutoring program. The program was studied in 27 schools in seven states between 2010 and 2015.

Academically, the extended day seemed to be a bust. There were no overall academic benefits in reading or math, on average. (There were some small benefits in math during the first year of implementation and for seventh graders.) 

Another five-year study of adding 300 hours to the school year in 26 Massachusetts schools indicated another bust. The schools used the extra time to increase English class to an hour and 45 minutes each day, for example, but students didn’t score higher on state reading or math tests afterward than students at comparison schools with a shorter school day. The one detectable academic benefit was higher science scores for fifth graders (but not for eighth graders).

The extra hours and days were costly, with schools not only having to pay teachers more but also coping with higher electricity bills from extra hours of running air conditioning. Longer days also cut into after-school sports and other activities, which are important for students’ well-being and motivation.

Snow days add another confounding factor to this research on learning time.  When students miss a lot of school because of snowfall, academic achievement suffers, particularly among low-income students. But that doesn’t mean that the opposite, adding days, boosts achievement. One theory is that lesson plans are built around the current 180-day, six-plus hour schedule. If you lose a day of carefully planned lessons, that’s losing a key building block. But as you add days, or hours, they’re not as well planned and utilized.

Researchers need to get a better handle on the amount of extra learning time needed to make a difference. Perhaps five minutes of extra time a day won’t do much but two hours might. Three hours could be too exhausting and counterproductive. Same with days. Adding five days might be worthless but 30 days could really help a student catch up. 

We need to nail down these numbers and produce better evidence if we want parental support for such a big change to daily and yearly schedules. 

This story about learning time was produced by The Hechinger Report, a nonprofit, independent news organization focused on inequality and innovation in education. Sign up for Hechinger’s newsletters.

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Jill Barshay is a staff writer and editor who writes the weekly “Proof Points” column about education research and data. She taught algebra to ninth graders for the 2013-14 school year. In school,...

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  1. In response to Jill Barshay’s fine article on the effectiveness of instructional time, it is worth pointing out that in science, time can never be treated as a variable. Time specifies an amount or a dosage of some other variable that one expects to have some potency. Any effort to increase instructional time without a clear idea of what the additional instruction is supposed to be is likely to fail. Teachers may not even use the extra time for reading or math instruction or may try to but without additional materials or lessons. Attempts to improve achievement should first decide what the action is that is supposed to increase learning and then should determine a proper dosage. Setting a dosage and then hoping the participants will fill it with something of value is not a recipe for success.

  2. These studies all suffer from the same design failure. The testing being used in these studies has little to no validity and almost no reliability. The length of time of these studies is also a serious flaw

    Serious researchers know these issues well and those who report on these studies need to know the issues so the reporting can be made more clear in the conclusions

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