If you want to do more than stuff your face and watch fireworks on the Fourth (not that there’s anything wrong with that), head to Holy Cow Yoga Center (10 Windermere Blvd., James Island) for some downward-facing dogs, crows, and sun salutes. They’re offering a free community class at 10:30 a.m.  It’s open to all levels, and it should last just over an hour. Get there early!