After parents kept coming in to ask whether the Mark Morris Dance Center in Fort Greene had classes for their children with special needs, the dance school decided to create a class to meet demand. The class, taught in eight-week sessions, is geared toward older children who have fewer options for extra-curricular activities and would have trouble keeping up in typical classes for dancers their age. Dance allows students to express themselves in ways that may not be possible otherwise as they deal with disabilities that include Down syndrome, ADHD and autism. The first full academic year of the Dance Fundamentals class ends in early June. Twelve students from Brooklyn, Manhattan and Queens are currently enrolled. Constance and Christopher Stienon of Fort Greene were among the first parents to register their child, Ysolde.