Longer school days help parents hold down full time jobs. A longer school year eliminates the need for babysitters or camps in the 10-12wk summer break, and also provides continuity of curriculum. Food is pretty easy and many schools are providing at least two meals already. A good number have things like backpack programs[1], also, to send food home (either in the evening or more commonly for the weekend).

[1] http://www.feedingamerica.org/our-work/hunger-relief-program...