On Monday and Wednesday afternoons, after school lets out for the day and classrooms fall dark and silent, Draper Elementary teachers shed their dress clothes — and daily cares — for tights and t-shirts and head to the gymnasium. For 30 minutes, they sweat, stretch and breathe to the soothing voice of yoga instructor Stephanie Williams who volunteers her time each week to provide these teachers a little time for themselves. “I love yoga,” she says, “I love teaching yoga.” The 32-year-old hatched the yoga-on-the-go idea over Christmas break with her mother, Draper Elementary Principal Christy Waddell. Williams was looking for…