How many days should school be in session each year?
It depends on where the school is located. And the difference between the shortest and longest academic year in the United States could be as many as 150 hours.
Over the course of a typical 13-year, K-12 academic career, those differences mean that students in some states end up receiving one-and-a-half years more of instructional time than their counterparts elsewhere.
That’s a key takeaway from new research that examines the findings from 74 studies related to instructional time and student achievement, as well as class time requirements in each state.
While American students spend, on average, 1,231 hours in school each year, there’s no national policy dictating how many days or hours students must attend classes each year. That’s a decision left to state lawmakers and school boards, which has, in turn, led to significant variation depending on where a child attends school.
As schools continue their efforts to ensure students are on track academically after years of disruptions caused by the pandemic, research generally supports the concept that the more time students spend in class, the better. But, the time is only valuable if used intentionally, according to the study’s co-authors, Matthew Kraft, an associate professor at Brown University, and Sarah Novicoff, a doctoral candidate at Stanford University.
The most “substantial impacts” from additional class time were felt at schools that had taken other steps to improve achievement, such as tutoring, increased school spending, and the replacement of underperforming staff.
But beneath such efforts to boost instructional time are the bare minimum requirements laid out in state law.
Sixteen states set the minimum length of the school year in both days and hours, while 10 states give districts the option to meet either a minimum number of days or total hours. Eleven states require only a minimum number of days without specifying the length of the day, and 13 states only set a minimum number of total hours, according to 2023 data from the Education Commission of the States.
Among the 37 states that identify a minimum number of days each year, 28 set it at 180. At the low end of the spectrum, Colorado requires 160 days while, at the upper end, Kansas mandates 186.
Explore each state’s instructional time requirements—and how much they differ—using the chart below, based on the data from the Education Commission of the States.
