(Portland, OR)  --  Classes will be held as usual today at Roosevelt High School in north Portland, even though a fire broke out there Sunday evening.  Portland Fire officials say a pile of materials in the school's gymnasium caught fire just after 7 p.m.  The materials were for a construction project that's being done in that section of the school.  School administrators say smoke from the fire didn't affect the rest of the school.  The cause of the fire is under investigation.