The New York Times reports that just a few years ago, school districts around the country were slashing summer classes as the economic downturn eviscerated their budgets. Now, despite continuing budgetary challenges, districts are re-envisioning summer school as something more than a compulsory exercise where students who need to make up lost credits fight to stay awake inside humid classrooms. According to the National Summer Learning Association, a nonprofit group, 25 of the country’s largest school districts — including Charlotte, N.C.; Cincinnati; Oakland, Calif.; Pittsburgh; and Providence, R.I. — have developed summer school programs that move beyond the traditional remedial model…