A. second lawsuit was filed Thursday claiming Stamford school officials failed to protect children from being abused by a public school gym teacher in the 1970s. The latest lawsuit, filed in Superior Court here, brings to seven the number of men who claim they were abused by the same teacher, Robert Martinez when they were children. All were between 8 and 10 years old at the time of the alleged abuse, according to the lawsuits. "Schools have a duty to supervise teachers but in this case Martinez was routinely allowed to call boys out of class and keep boys after gym class so that he could be alone with them in his private office where he molested them," said Cindy Robinson, who represents the seven plaintiffs. She said she anticipates filing more lawsuits against the school system as more victims of Martinez come forward.