MARION — Linn-Mar High School started fall classes Monday with new arts and industrial technology labs on the north side of the school, all completed about two months ahead of schedule.High School Renovation Project Manager Chad Schumacher showed slides of students filling new arts, metals and engineering labs to school board members at Monday night’s meeting.The slides were in sharp contrast to mid-July, when board members donned hard hats and toured a powerless, debris-strewn construction area for an update on the high school’s $30 million renovation project.“Not everything is in the cabinetry we finished installing over the weekend,” Schumacher told board members.