When Marblehead merchants started making plans to sponsor four big festi- vals along Main Street this season, they turned to Sande Measimer, who teaches art at the Danbury High School and Middle School, for some special help.Grant McCallum, of Jodie McCallum & Company Fine Art Gallery, and secretary of the Marblehead Merchants Associa- tion, asked Measimer if any of her stu- dents would be interested in designing logos for the festivals. The idea was to involve young people in helping to pro- mote their community.