The classic Rogers & Hammerstein musical “Oklahoma!” will run through Aug 18 at The Barn Theatre. Driven by a romance between Laurey, who lives with her Aunt Eller and cocky cowhand Curly, it contains some of the most famous songs in the American musical canon, such as “Oh, What a Beautiful Mornin’,” “The Surrey with the Fringe on Top,” “People Will Say We’re in Love” and more.