DENVER - Hundreds of high school students in Colorado´s second-largest school district staged a walkout on Wednesday to protest proposed changes to a history curriculum that would stress patriotism and discourage civil disobedience. Student protesters marched outside schools waving placards bearing slogans such as: "My School, My Education, My Voice!" and "Don´t Make History a Mystery!" The demonstrations marked the third straight day of protests at six high schools in Jefferson County, a suburban Denver school district of 84,000 students. The controversy stems from proposed changes to an advanced placement history curriculum proposed by a school board member who was