Reviving an old tradition, the Florida Ballet brown bag lunch concerts returned to its studios Thursday with a preview of Saturday evening’s performance at the Florida Theatre. Florida Ballet dancers presented excerpts from the show “Spectrum” for the lunch crowd. Classical, neoclassical and modern numbers were part of the preview. Saturday night’s show begins at 7:30 p.m. Tickets are $10 and $20. The show features a selection from the classic Russian ballet “La Bayadere,” “Bolero,” a contemporary piece inspired by the neoclassic repertoire “Spring Waters” and will showcase the premiere of “Divertimento,” a project which places the orchestra on the stage.