It's officially back-to-school season. Kids all over the country, no doubt, are dismayed.

A lengthy summer vacation is considered an indelible part of the American school experience, a time to make treasured memories at summer camp, sports retreats, or family trips. But here's the thing: Summer vacation is screwing up the education system. It's time for America to embrace a longer school year.

Contrary to popular belief, the summer break in America's schools has nothing to do with the agrarian calendar, which would have found it optimal for students to be schooled in the summer and winter while working on the farm in the fall and spring. In the late 19th century, a push among reformers for a standardized school year led to the current schedule, with school out for the summer due to the fact that many city-dwellers departed for the country during the warmest months of the year or were loathe to have their children take classes in buildings that would be stiflingly hot.

That the schedule persists today is due to a number of factors: inertia, with so many systems built to serve the calendar as it already exists; supposed resistance to change among parents, teachers, and school administrators; and the reality that a longer school year requires bigger school budgets.

That doesn't mean it shouldn't change.

There's a significant downside to the current schedule. Loads of academic research shows that summer vacation does students no favors, as they tend to forget a chunk of what they learned during the year in what's known as "the summer slide." Since 1906, researchers have explored the question of what students forget over summer vacation, and some studies put the amount of learning lost at as high as 30 percent. At a minimum, summer learning loss ensures that teachers must spend the first weeks of school reviewing the previous year's material to make up for what evaporated in the summer heat — a massive inefficiency inherent to the summers-off schedule.

The loss is more acute for students from lower-income households. Parents with more resources have the ability to pay for enrichment programs over the summer, but these programs don't come cheap, generally costing parents thousands of dollars per year. For some families, these programs are simply out of the economic question — and the existence of summer vacation bakes those socioeconomic disadvantages right into the education system.

Studies have also shown that summer learning deficits accumulate over the years, so students who are starting from behind keep sliding further and further. And that's leaving aside the fact that students who depend on other programs at their schools, like low-cost meals or after-school care, end up simply going without when school is out.

The debate over extending the school year is often disingenuously portrayed as a call to have American students spend as much time in the classroom as their peers in other countries. But American kids already spend about the same amount of hours in the classroom as do students abroad. The problem isn't that American students need more time in the classroom, it's that their time needs to be distributed differently. Some schools that have experimented with year-round school schedules opt for 45 business days on and then 15 off, while others have tried a 60-20 or 90-30 split. The shorter breaks minimize the amount of time for students to forget what they've learned, while still maintaining roughly the same amount of overall time in the classroom.

To be sure, extending the school year is no simple thing. There would be administrative costs associated with the switch, and teacher salaries would need to go up to account for the change in their schedules. Hopefully that latter step would help alleviate some of the resistance teachers have put up. But as an example, in Washington, D.C., very few teachers abandoned schools that switched to a year-round calendar even when given the chance, a result in line with many other school districts.

In hotter climes, meanwhile, extra spending on air conditioning would likely result from a longer school year. The federal government should pitch in on such infrastructure needs. These are not insurmountable obstacles; thousands of schools have already tried some version of year-round instruction, and we can use the success stories among them as templates.

Inevitably, not every parent prefers year-round schooling. But many do. In 2014, a Gallup poll conducted in tandem with the professional educators' organization Phi Delta Kappa found that a plurality of Americans, as well as specifically public school parents, favor shortening the summer vacation in order to add more days off elsewhere.

Year-round schooling is certainly no panacea for what ails America's education system. For the schedule switch to truly work, it would have to be implemented everywhere — a mandate directly opposed to America's tradition of letting states or local school districts decide such things. Studies also show that, absent other efforts, it may not raise achievement rates; data have gone both ways. Don't be fooled into believing that a switch to year-round schooling will alleviate the pressure to take other steps to close the achievement gap.

But a longer school year would address one big flaw: Summer vacation doesn't really serve America's educational interests, and it actively harms the most vulnerable students. Sorry kids: Break's over.