Francesca Todesco, longtime member of the Sokolow Theatre/Dance Ensemble and Dances by Isadora, celebrates her 20-year journey in the American Modern Dance Scene with two performances of works by Isadora Duncan, Anna Sokolow, Catherine Gallant, Jim May, and a world premiere by Rae Ballard.   Joining Ms. Todesco are dancers from the Sokolow Theatre/Dance Ensemble, Dances by Isadora, and Thoughts in Motion Dance Company.   All works will be accompanied on piano by Nathaniel LaNasa.