The idea that the typical American school day is too short is far from a new idea in education circles. But it’s certainly gaining popularity, backed by recent studies that have found improvements in student performance when kids spend more time in school. However, ongoing tensions remain over whether American schools need longer days—or, rather, strategies for being more productive with the time already allocated. As with many debates about education, the answer probably falls somewhere between those two extremes.

American students spend an average of about six-and-a-half hours at school each day over a 180-day calendar. In Boston, for example, the typical school day is six hours for elementary students, with middle schoolers staying in class an extra 10 minutes. The city’s high schoolers average a six-and-a-half-hour day.

At schools across the country that have extended their classroom time, the typical day is just under eight hours, while 40 percent of those campuses have students for more than eight hours daily, according to the National Center on Time and Learning, a nonprofit clearinghouse and advocacy organization. What hasn’t increased significantly is the length of the school calendar, which hovers around 180 days for most schools. (And that’s why summer learning loss is a whole other problem.)