Undoubtedly, some of the extended day ought to be used for academic purposes, some for social, and some for plain old ‘fun’ activities that children don’t always get – like karate classes, French lessons, ballet, and so on. Additional school time need not be dominated by academics, i.e. teachers. A variety of support staff can be used. In fact the Globe had a good piece on this topic the other day. See here.
But in Boston, the issue has now boiled down to whether or not teachers ought to be compensated for their additional time. Other professionals are compensated for their additional time: dentists for additional cavities filled, lawyers for additional cases taken, nurses for additional shifts assigned, plumbers for additional water pipes installed, and so on. And teachers ought to get similarly compensated for teaching additional classes.