Chattahoochee Elementary School students had to let sleeping dogs lie Tuesday morning. It was a challenge for the first-graders to focus on learning and ignore the visiting canines from the Forsyth County Humane Society. But despite a few noisy moments, the students were engaged in the lesson, largely led by volunteers from the society.Volunteer William Buck talked with the children about approaching pets, helping them learn the signs a dog will give that they could be a danger.