Peter Orszag advocates for increasing the length of the school day by about 2 hours.
As a teacher, I know I would appreciate a little extra time in all my subjects. Based as my experience as the sole teacher in a middle school classroom, I think about how much more we could have done with the extra time to round out the curriculum. But I think it only makes sense to add those two hours if they’re used properly. More of the same — like sitting at desks — is unlikely to help a lot.
Orszag points out that there’s some evidence (see Dobbie and Fryer, 2011 (pdf) and Fryer, 2011 (pdf)) that longer school days have improved student performances. But it’s crucial to note that the longer days are part of extensive changes in the curriculum that I don’t think can be separated from the other changes: “frequent teacher feedback, the use of data to guide instruction, high-dosage tutoring, increased instructional time, and high expectations” (Dobbie and Fryer, 2011); “a more rigorous approach to building human capital, more student-level differentiation, frequent use of data to inform instruction, and a culture of high expectations” (Fryer, 2011).
When I think of longer school days, I tend to think of a more apprenticeship model. Giving students time to work on personalized projects, interacting with experts as they need.