PALAISEAU — A schoolteacher whose body, face and tongue are covered in tattoos and who has had the whites of his eyes surgically turned black said he was prevented from teaching at a French kindergarten after a parent complained he scared their child. But the teacher, Sylvain Helaine, 35, still teaches children from the age of six up, and said that, after an initial shock when they see him for the first time, his pupils see past his appearance.