Many children across the U.S. are getting ready to head back to school. But here in Northern Virginia, public school doesn’t start again for another four weeks. Still, the summer has seemed to fly by for us. For one thing, it’s a week shorter this year: Our district shifted the school calendar so that school will end a week a week earlier in June and start a week earlier (the week before Labor Day). But because the 2016-17 school year…