Marty McFly PFC.Verne hates taking dance lessons and asks Doc and Clara for his help. Doc tells him that he once had "blueprints" for a dance machine that helps one to remember the steps but the blueprints were lost in a fire when Doc was a young man. Verne and Marty head back to 1944, where Verne has the opportunity to meet his dance instructor, Dorothy, when she was a young girl. Escaping from Sergeant Tannen and the blackout warden, Marty accidentally joins the Army, while Verne goes to the movie theaters. When Verne dances with Dorothy while watched by Rosie, Marty begins crying in the Army. Meanwhile, Verne rescues Marty from being drafted. At the Hill Valley Jitterbug Contest, Verne wins the trophy and gives it to Dorothy, who is with her sister, Rosie. He and Marty head back to the parallel future in Hill Valley. Bill Nye Segment: Examining the center of mass.