KELLER - Willis Lane Elementary recently earned designation as a Green Ribbon School because its students are practicing earth-friendly behavior, getting regular exercise and enjoying the great outdoors.   As the school community worked at recycling, reducing waste and fitness, students took some of those habits home with them. For Eco-Campus, a focus on conserving resources and recycling, Willis Lane officials promoted a "Waste Free Lunch and Snack Week" that encouraged kids to bring food in reusable containers. They also had an emphasis on recycling, starting up a new program with Terracycle to recycle lunch kits, drink pouches and other items, adding more bins around the school and allowing parents to recycle old computers, batteries, small appliances and other electronics.   Willis Lane Principal Cheryl Hudson said, "It took them from everyone recycling paper to we can recycle a water bottle, Capri Sun pouch, a Lunchables container and a lot more."