MADISON, WI (AP) -- A high school principal admitted erring in letting a Marine Corps recruiter conduct a physical education class, but some parents said they remain concerned about the move they called a backdoor effort to recruit students. School officials shouldn't have let the recruiter and other corps members conduct the classes, which one student said featured an obstacle course and members "screaming" at students "totally Marine-style," said principal Alan Harris of Madison's East High School. "We made an error. We're going to act to ensure that it doesn't happen again," Harris said, who said "a handful of parents"...