It was the last Sunday in July, and Bethany and Garvin Phillips were pulling price tags off brand-new backpacks and stuffing them with binders and pencils. While other children around the country readied for beach vacations or the last weeks of summer camp, Bethany, 11, and Garvin, 9, were preparing for the first day of the new school year at Griffith Elementary, just six weeks after the start of their summer vacation, the New York Times reports. Griffith, one of five schools in the Balsz Elementary School District here, is one of a handful of public schools across the country that has lengthened the school year in an effort to increase learning time. A typical public school calendar is 180 days, but the Balsz district, where 90 percent of the students qualify for free or reduced lunch, is in session for 200 days, adding about a month to the academic year. According to the National Center on Time and Learning [1], a nonprofit research group in Boston, about 170 schools — more than 140 of them charter schools [2] — across the country have extended their calendars in recent years to 190 days or longer…